Is he waiting for me to leave my boyfriend? Confused..?

He probably likes you and knows you're in a relationship. He's struggling to honor your relationship: when he ignores you and stuff he's doing it to try and get his mind off you, but when he talks and flirts he collapsed under his desires. However, I wouldn't leave your bf for him. If you can make a four year relationship work, you're pretty set. Maybe your bf is waiting for the right time? Or perhaps needs to save for an engagement ring? They aren't cheap, you know :P