Sorry to give bad news but if a guy introduces a friend to a girl it means hes trying to hook up his friend with the girl. Its not good, like you think hes trying to get closer or feels more comfortable around you. At least 80% of the time this is the case. Trust me, I'm a guy who has had a lot of experience on both the giving and the receiving end (no homo, it wasnt meant to sound wrong or gay). Don't get too worked up, but dont let yourself get any closer to him. Unless he starts giving you signs or sorta comes on to you, it might mean he isn't interested.
Don't get clingy. The way you say it its not like your in love with him or anything, so if in the meantime you meet another guy you like, and you think its actually going somewhere, let something happen. Don't ignore him just because of this guy who is probably trying to hook you up with his friend.