He sounds a lot like me at that age to be honest.
I was also the nerdy guy, who'd had very little interest from girls when I started uni. Unlike your son, I'd had one kiss from a girl in a nightclub, we promptly lost track of each other and when I found her again, she was kissing one of my friends, which didn't feel great.
I also felt like a bit of a loser, and the fact that women weren't interested in me did leave me feeling somewhat morose, especially when I'd had a few drinks in a club and seen all my mates snogging women.
But the fact was, that I wasn't doing anything that would interest a woman. I was shy, I was quiet, I was generally content to let others carry the conversation, interjecting only occasionally. It was no wonder that I wasn't getting any interest. I wasn't doing anything that would make me stand out from the background. I could be quite funny, quite interesting, but only really one on one, with trusted friends.
What changed was an evening out towards the end of my first year. I'd been a part of the Balti Society all year (we went to pub, and then for a curry, that was it). I'd gotten to know a good few people through it, but we didn't tend to see each other outside of our curry nights. Well, on one of these evenings in the pub after a curry, I was deep in conversation with one of the girls who I'd always thought was so far out of my league, and she said "You know, if we'd ever spent any time together not stinking of curry, I'd probably have kissed you by now". A few days later, I bumped into her in the Student Union bar, she pointed at me and said "You owe me a kiss!". A week later we ended up in bed together (stinking of curry).
Unfortunately that was the end of the year, and she didn't come back for our second year, but I'd now realised that women did like me, they just needed to opportunity to get to know me.
I'm sure your son will likely come to this realisation at some point as well OP.