Why is my brother spending time with a friend too much?

My parents are kind of worried that at the age of 21, he hasn't gone on a date yet. He's a very social guy and would have no problems getting dates but he never brings a girl home. His excuses are always ''I just find none attractive'' or ''I'll being her one day'' and changes the topic. I don't recall him ever being attracted to any girl from our school nor any in general.

Then he's been spending too much time with his same friend Lucas. He has other friends but it's that particular guy he talks to more than average. Secondly, he spent the night twice at his house and didn't come up back till the next day or 2nd day. Lastly, he gets overly happy with talking to him on the phone and locks himself in the room, too much attention for a friend.

Why is he spending too much with that particular friend?
Updates
1 y
Well he's going to turn 22 soon on August 1st. He was just talking on the phone with Lucas again just 30 mins ago and again locked himself in his room.
Why is my brother spending time with a friend too much?
Post Opinion