As an overthinker myself, I do find myself attracted to people who are more carefree... Which means they sometimes fail to take me in consideration, which is why I imagined that happening. No judgement on those girls, because he's likely fulfilling a need of his own (maybe a superficial one over one that would be more fulfilling over time?) when he seeks them out. Doesn't mean every impulsive person is thoughtless, either, just that overthinkers might require more careful handling.

I don't think I could give any pointers towards steering him to help, other than he must be seeking out change himself. If he's perfectly fine with the life he leads, you can personally think it kinda sucks that he won't find x, y or z, but chalk it up to personality differences. If he's happy, great. If he's constantly coming to you with relationship woes you can totally draw up boundaries. "Friend, I think you deserve better and it pains me whenever you settle for less and expect more and it takes a toll on me to be supportive, so I will no longer discuss relationships with you".

Again, you seem super great and I think expanding the social circle and just being great friends who also introduce him to more great people is likely to have a positive effect over time Just because I'm a curious kitten, may I ask what the group cosplay is?