Okay, Captain Save-a-Ho. First step is to move out. Get your own place. After that, build a harem.

This is sad. Look man I stopped at the part where you read her messages meeting another guy for dinner. This is over. Early this year? Stop wasting your time.

You need to go to the gym and get fit and get other options so you aren't so desperately clinging to this woman as your only source of intimacy. Read the sidebar

This is sad bro, you should have dignity and leave now...

I lean towards accepting the offer of sexual opennes

NOOOOOOO!!!

This always, ALWAYS works in the woman's favor and against yours. It always means she has several alternative dicks picked out and lined up. Whereas for your part you have to work to get into a woman's pants then work harder to keep the plate spinning on a part time basis.

The solution to your dilemma is to withdraw from your overinvstment and overcommitment to this woman who is obviously not reciprocating it. No announcement, no drama, just set about lining up your own place to move on to, and remain focused on this new mission.

You'll likely find she suddenly gets really interested in you again as she senses the imminent loss of her pay-pig and doormat. Maybe take advantage of sex thus offered but don't rekindle any sense of commitment. Main problem with going for the sex is her playing the I'm Pregnant card.

Bottom line, pack your bags with the remnants of your dignity and move on!!! This woman has already checked out of any commitment to you.

We've probably all been in those shoes at some point.

I will waste some time 2 give you some advice you probably won't take because you're such a mark but here it is. The 1st thing I noticed is that it appears that you think that you have some chance to improve your sexual status with this woman. You don't. You must understand that she is utterly uninterested in you sexually & never was, so any idea of "reigniting" isn't rooted in reality. You yourself stated that sex is scarce but she has an "adventurous past". You try to blame it on the "pill" but when did she start taking this pill? Definitely not at around 34 but I'm sure she told you something like that. If the pill is killing her libido why is she finding time & energy to rendezvous with multiple men besides you? I used to date someone whose libido was threatened by pills; she actively looked for alternative treatments to ensure her sexual level was up to par to do what we both wanted to do together so this excuse is nonsense.

Not only is she not sexually interested in you, she doesn't respect you. You aren't a beta in her eyes, you're closer to an omega. If you were beta with some respectability in her eyes, she wouldn't be so sloppy with her lies & sneaking around & she definitely wouldn't push the idea of open relationships. Respectable betas get the decency of getting cheated on the traditional way: behind their backs in max secrecy. Females push open relationships first when they are confident it would be difficult for the man to get ANY female, much less one comparable to them. Your relationship with her is the equivalent of a homeless yet attractive man (hobosexual) starting a "relationship" with a fat woman with her own place.

With all this being stated, your questions can be easily answered.

1. accepting sexual openness would be irrelevant because she has (accurately) concluded you can't get anything else. I'm not tearing you down: in the mental state you are you can't.
2. You never had frame to regain, see above explanation. This relationship wasn't full of hot sex in the beginning before it fizzled to this, by your own admission it was always sexually scarce. Thus, breakup immediately.
3. You can't set rules without respect or authority & you have none.
4. Yes but that is because there once was a relationship based on desire, respect, etc. This "relationship" never had any of these. You mistakenly believe that you have a chance at scoring women. As I alluded to before I believe you have a well below average chance at that & she does too, which is why she pushed the idea of an open relationship.
5. You've been chasing validation in all spots. Save your dignity & leave.

You need serious personal help. You lack confidence, self-esteem, & various other integral factors. You should refrain from dating until you resolve these issues to avoid falling into the same trap w/another female.

This is a fucking disaster! She's making you a cuck, lying to you, cheating left and right and she doesn't give you sex. Why the fuck are you staying? This chick offers nothing except suffering and frustration. Have some fucking standards. Move on from this mess.

Read the sidebar and don't accept this kind of bullshit treatment. It's not cool.

I think the analogy of the frog being boiled to death so slowly that it doesn't notice the change in the water temperature applies here. You would never have bought into any of this at the outset but she is constantly making things a bit worse and because its only a bit worse each time she lies and cheats and you are invested, you keep going.

She isn't full of desire but she wants to see other guys. Either she is not that into you sexually or the novelty, conquest and attention side of sex is more interesting to her than the reality of having sex.

This is not going to work for you I am afraid. You are becoming a police man, even though all you are saying is perfectly reasonable. She might even turn it all around on you and call you controlling or coercive.

You can't win with a modern woman who wants to cheat. You have no rights to make her play straight. She can do as she pleases, you can't even demand to know the truth. You only salvation is to walk. I am sorry about this but she will make a fool of you if you stay with her. Don't take that Devil's bargain of the open relationship. This will just take you into hotter water. You will pay bills for a cold slut and jump through hoops to court hopefully warmer sluts for casual sex. Its the worst of both worlds

As usual, the answer is "Next".

Once a woman has lost the essential combo of desire/respect for you, (in this case she probably never had it, holy fuck) YOU ARE NEVER GETTING IT BACK. There is no magic pussy password to get it back. Accept that and move on.

The abuse of your devotion and good will only get worse, not better if you stay. Put on your best poker face, and quietly fix your shit by arranging things so that you getting the fuck out with as little warning and fanfare as possible.

No long heartfelt rom-com discussions. Life isn't the fucking Hallmark channel, so don't rely on shit that would only work in a world made out of fem-centric fiction.

And maybe actually read the god damn sidebar and make even the barest effort to comprehend it. Had you done so, you could have avoided getting into this shitfest of a situation to begin with by recognizing that she was not worth anything from you and having the self respect to pass on her shit.

A woman that is worth a damn doesn't make it necessary to police her or do things that put her fidelity in doubt.

Thanks for the feedback and for taking the time to reply. Most of what you said I already thought myself, but hearing it from a third party really clarified things.

Bottom line: the right move is to get out. I’m getting nothing here - no sexual compatibility, no stability (when I ruptured my tendon she spiraled instead of supporting me), no value in finances, housework, or cooking (I do better on my own with simple clean protein heavy dishes). She’s social, but her friends aren’t my crowd.

I guess I was intrigued at first by her sexual openness in the past, thinking maybe I could share that kind of lifestyle with her. But that never happened, even though it was dangled in front of me at times.

On the “open relationship” point - she never really framed it as that. It was more like, “you can go get it elsewhere since I have no libido - but I would apply to her.” But probably: this is how it starts, and eventually it’s either, “Well you’re doing it so I should too,” or she just uses it as an excuse for her leisure activities with male “friends” to drift into being lovers. Either way, it’s lose-lose as you said: I’d be paying bills for a cold woman at home while jumping through hoops to chase casual sex outside. That really clicked with me - worst of both worlds. I can do casual dating on my own terms without dragging her dead weight along.

I’ll admit I’m still tempted to try us the time until the exit as an experiment, just to see how much she’d actually would support it. She dangled the idea of a threesome in front of me before. So part of me thinks: fine, put your money where your mouth is. “You were adventurous before, and I get that your libido is low now, but sex is essential for me. You’ve got more experience in that world, so if you’re serious, help me. Do you know friends or people from the past who would be open to it. No, help with the apps, with the photos, even introductions.” That way at least I’d learn something, even if it’s just a lesson that this was all the bait. And if not - worst cases she introduce me to sexual open minded friends with less work for me.

But long story short: this relationship doesn’t align with my core values - support, honesty, and trust. Without those, there’s no long-term future. I need to act on that. Set up my exit, and if I choose, run a few “experiments” on the way out so I take lessons for the future. And until than set clear boundaries, I will have to think about what they are.

Thank you - your perspective helped me a lot to get clarity & take action!

Anytime a woman says "I need space," it's over. The rest of what you wrote just confirms that.