Ok let's translate what probably actually happened. No girls don't usually end long term things for just one shitty night or some moderately weird or shitty thing if they're actually attracted and happy with the relationship. What they do do is wait for a bit, knowing they're not attracted to the guy anymore, waiting for him to do something (or baiting him into it), waiting for an excuse where they can put the blame on them more directly and be like "see this is why we're breaking up" (usually while they're weighing their options with another guy they have eyes on.) Also makes a more convenient thing to tell their friends and family aside from "I was bored shitless and wanted to fuck other dudes". Lol

OP it was probably over long before that. You seem like a nice guy so I'm guessing there weren't big fuckups beyond just being boring and unattractive. She's already lost attraction, looking for a convenient way to end things. You take her out for the whole smorgasbord of nice guy gestures. Cooking for her, taking her to a garden (lol), buying an expensive dinner, going out and buying drinks for everyone. Followed by crying, making her friends see you as lame and embarassing through whatever behavior you're doing, and being super needy and clingy (that's what love bombing is, isn't it?), Followed by going to bed without fucking the shit out of her. Yes it's nice to take her out for her birthday, but if she's already lost attraction for you, basically all of these are icks. Regardless of whether you were drugged or not. Getting drugged is obviously a good escuse for your behavior and is shitty, but that doesn't stop her from feeling the way she feels in the moment. Attraction ain't a choice.

I'm sure it was obvious he was more fucked up than he should be, so why else would she try to reframe it as a "psychotic episode" and "love bombing". Both of these make you out to be a clingy, fucked up, needy, weirdo, which fits nicely with her desire to break up with you. A healthy relationship where she's attracted, she goes "wait something's wrong. We should get OP home". Instead she just...allows you to basically self destruct the relationship. Yeah sorry op but this shit was over for a minute.