Used to be me.
Honestly the dude just needs a challenging routine.
Its the only way.I highly doubt its just females, he's likely socially incompetent. What changed my life was changing my routine. i did lose weight, start the gym and that helps but it can also hinder you. Soon as you start to slip or lose gains you'll feel the same. u gotta get comfortable with yourself.
I stopped staying inside, and started joining things. And just walking around to different places. I also started hanging with more social people. Before I knew it, women were hitting on me and I went from 0 confidence to some hood level of arrogance.
I remember when i finally got confident, I would lowkey talk to a chick for 5 minutes, and hit her with the, so when we fukking? my place or your place?

still had 0 game then but

I started to pull.
Just gotta get homie to realize people see him differently than he seems himself.
I've been where your cousin is except not to that extent. Growing up I was a fat kid who got made fun of all the time. Played football in high school got in shape, but took a ton of shyt for other reasons. I thought I was the ugliest dude ever had no confidence.... Then one day I said to a friend that I thought I was ugly. He came back at me and said "My mom seems to think you're actually a really good looking guy man."
That changed everything for me for some reason. All it took was one person that wasn't a family member to pay a complement and for it to be sincere. I attempted to start talking to women, and got good at it over time to the point that people call me charming now. Also being damn good looking helps. Tell him to hit the gym or find something he's passionate about and get good at it.
Kids are fukking cruel man, and that kind of shyt can really fukk you up. I'm tougher for it now, but there was a time where depression was a way of life for me.