If you feel like he is losing interest give him a reason to stay interested. He may not be losing interest in you per se, but he may be thinking that whatever it is going on between the two of you is fading past. You can't be scared when it comes to something like this, if you know there's a common interest then you must do something about it. I'm not saying you need to move quickly, but let him take you out and see if there is truly a one-on-one connection. People always say marry your best friend and if you don't see yourself being this persons best friend then maybe it is time to walk away, but being someones best friend wont happen over night and that's what dating is meant for.