Guy at my kickboxing gym?

At the kickboxing gym that i train at, there's this guy who is my age (17) and he's always really nice and talkative with his mates and the older women that he sometimes partners with aswell. But, i've partnered with him a couple of times and im not sure what im doing wrong im always freindly but he just shuts off with me and it seems to be only me :( i don't get it because i know he's not shy after seeing him talk to everyone else, but like whenever i even just smile and say hi to him he'll just look suprised or glance away... i know he sometimes talks about me to his freinds at the gym, and i catch him checking me out or even just looking at me quite often. BUT IT SEEMS LIKE HE WANTS NOTHING TO DO WITH ME :( im not fishing for a realtionship, just trying to make some freinds at the gym who are my age, because there are no other girls my age, but he's kind of making it hard for me, and i think it would be awkward to approach him when he's with his group of guys who i dont really know at all. what should i do?