From an epigram about the oneitis of guy named "Rufus" by Martial (38-102 AD), an ancient Roman writer:

Quidquid agit Rufus, nihil est nisi Naevia Rufo.

si gaudet, si flet, si tacet, hanc loquitur.

cenat, propinat, poscit, negat, innuit: una est

Naevia; si non sit Naevia, mutus erit.

scriberet hesterna patri cum luce salutem,

‘Naevia lux’, inquit, ‘Naevia lumen, have.’

haec legit et ridet demisso Naevia vultu.

Naevia non una est: quid, vir inepte, furis?

Translation:

Whatever Rufus is doing, for Rufus there is nothing but Naevia. If he’s happy, if he’s weeping, if he’s silent, he talks of her. He eats his dinner, drinks a toast, asks a favor, refuses one, makes a sign: it’s all Naevia. If there should be no Naevia, he will be dumb. When he wrote a greeting to his father yesterday morning, “Naevia, light of my eyes,” says he, “Naevia, light of my life, good morning.” Naevia reads this and smiles, lowering her face. There’s more than one Naevia. Why, silly man, are you such a fool?”

Notice how in the epigram, Rufus is writing Naevia little notes every morning: "Naevia, you are the light of my life." This is exactly what millennials do: text such sentiments to their girlfriends every morning.