He's a grown man acting like a child who wants to pretend he's too cool to have fun and be a normie, and is super embarrassed when he realizes he broke his character, so to speak, and she just gets sopping wet at the thought of it.
Yes, he built a façade of a stoic and taciturn man, but it all crumbled down when he got intoxicated. He feels shame because she has seen his true side.
His 'hidden side' leaked towards his 'open side', per se. He knows he's talkative and enjoys social contact, but he is too anxious (?) to do it by himself (or wants to look cooler) so he needs something like an enabler (cute co-worker, alcohol, etc.) Refer to JWM:
I have no idea what I'm talking about. I've made this all up.
That's fascinating! I never heard of the Johari Window Model before, and was happy to learn something (especially in a super unexpected place). Thanks!
meh. IDK, maybe if we had a page or two of him opening up I'd "get" it. Talkative drunk is probably the least embarrassing kind of drunk as long as you're not harassing someone