What is one relationship you regret?

This guy was a friend of a friend in college and when I met him he was really funny and cute and kind of nerdy and his parents were a coach and a teacher which I related to because my mom was also a teacher. He seemed pretty normal at first so when he asked if I'd be his girlfriend after we got drunk one night I said yes.

Ok so then things get weird as I start getting to know him. He was a waiter so he worked weird hours and he came over to my apartment one night the first week we were dating and he's kind of wild eyed with what I thought was passion and we had sex for the first time but something was off about it like he wasn't "present" for it and then he talked my ear off afterwards and weirdly energetic. When I'd go to his apartment to hang out in his room we'd be talking and if I even got near his drawers or closet he'd get really weird and panicky about it. I'd be like "Do you have a bottle opener around here?" Start barely looking around and he'd freak and make me sit on his bed while he got it. He'd go to the bathroom and lot and then be really silly afterwards. I would stay there at night and share his tiny twin bed, he was probably 6'4, and he'd want to smother cuddle me the whole night, which I hate because I get hot and staying in one position makes my back hurt. Anyways we dated three weeks and then he kind of stops answering my texts and I go to see him at his apartment and his best friend turns out had kicked him out because he spent all of his money on drugs and hadn't paid his rent in a long time. He was living out of his car addicted to cocaine and who knows what else pill wise.

I didn't know a damn thing about drugs so everything went right over my head especially him being protective of his storage areas and the first time we had sex he was high out of his mind. I'm still pretty embarrassed that I missed the red flags.

Tldr: I dated an addict and didn't realize until almost a month into dating him what was going on

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