TLDR: I went home for Thanksgiving. While home, I fucked my high school girlfriend even though she has a boyfriend. While she was laying on my chest, she told me all about how much she likes him.

Body:
Quick backstory. Back in my high school days (now a college Junior) I had a very BP relationship with my high school sweetheart. I was dominate in the relationship but it took 3 years of friendzone before we started dating and there was one hell of a rough start. Anyway, we dated for about a year and a half. We broke up halfway into freshman year of college and she became my first ever plate. She's always been a very good plate because we only see eachother during breaks and I always come back into town more attractive than I was when I last left. It's like winning a break up every single time. It's great.

Fast forward to last week. Went home for Thanksgiving break. She told me a month or so ago that she started dating someone. Good for her, if she's happy then I'm happy for her. Whatever, don't really care. I send her a snapchat of the airport when I land and she immediately texts me wanting to see me while I'm home. Green flag for me, red for him. I've never knowingly been the cheatee and always felt that it takes one hell of a douchebag to do it. Since TRP, my opinion on the matter has changed. Cheaters gonna cheat. So I decided to see what I could do. I wanted to shove that bitter AWALT pill deeper down my throat. I really thought she was a unicorn, I wanted to prove to myself that they don't exist.

I followed the guide /u/dr_warlock posted to a small extent. I knew that this wasn't a standard interaction, so I didn't treat it as such. I responded after an hour or so and made tentative plans for that night, knowing that I would cancel. A few hours later, things got interesting.

I cancelled the plans in order to spend time with my family and said maybe we could hang out later that night once everyone is asleep. She was bummed and sent me a snap of her shower with the caption "So many memories..." (we fucked in her shower a lot in high school. Shower sex is tight.) which I ignored. Later that night, she asked what I was up to:

"Thinking about what I'd be doing if I came to your place and took advantage of your parents being asleep."

"oh...like what?"

"I'd rather show you."

She wasted an hour or so trying to get it out of me instead of asking me over, and when she finally did I said I was too tired. Fuck that bitch. I told her we could get coffee 2 days later.

The next day, I hung out with another girl I'd been talking to. Made out but no sex (parents were home). The day after she came over in the morning when no one was home and we fucked like rabbits. Fantastic sex marathon to start off my day. She leaves, and I went to coffee with my ex.

It's amazing how casual everything feels when you've already nutted 3 times by your coffee date at noon. We talked and I was very disinterested the whole time (shit, I was done for the day. She's boring.) Everything was going fine, nothing spectacular, until the other girl walks into the coffee shop.

Totally unplanned. Turns out she used to work there and loves their coffee. So I see other girl and start cracking up. Ex couldn't figure it out until she saw the other girl blushing. Then it all dawned on her. She was pissed, and it was perfect.

"What hell? When did you hook up with her?" (normally I wouldn't answer, but this was perfect.)

"Uhhhh looks at watch about 2 hours ago."

"You're such a slut." feign disgust

So we talked for another ten minutes or so and went our separate ways. She was annoyed, but I knew it was a good thing so I let it fester. This is turning into a book, so I'll fast forward to a few days later.

She came over, we spent the day hanging out. She kept trying to touch me and I firmly shut her down every time. I friendzoned her for a few hours and she couldn't handle it. I let her touch me more and more as time went on but would occasionally push her away. After a few hours of her trying to touch me while I was watching football, she started floating her lips closer to mine. I let that go a few times before I kissed her hard, and she came right back. Game on.

20 minutes later her panties are torn off (Sex God Method style. Do it, it's fucking awesome.) and I'm fucking her brains out. She was wetter than I had ever felt her and was begging me to pull off the condom. That's a new one from her.

Afterwards, she laid on my chest on the couch. This is the shit that I still can't wrap my head around. I offhandedly mentioned getting another girl over and having a threesome. At first, she balked. Then she warmed up to the idea and admitted that "it would actually be really hot...". She had never gone that far before. Immediately after that, though, she said "...but that'd be cheating!"

Rewind. We just fucked. She was laying naked on my chest. She had actually split the situations in her head to a point where fucking me isn't actually cheating. The sheer cognitive dissonance blew my mind and I'm still trying to wrap my head around it. Then she went on for like 10 minutes about how much she likes this guy. Whatever, it was all bullshit. She probably just didn't know it.

Lessons Learned: If you're a beta boy, you're fucked when an alpha inevitably comes along. If she's had better dick than yours, there's a much greater chance of her cheating. And even if she hasn't, all guns are loaded.

I can't believe I once thought about marrying her. I can't believe I once thought about marrying.