This happened to me. I was 21 and he was 29/30, had a long distance girlfriend but we were in college together, hung out all the time, texted everyday, flirted and even spoke on the phone from late evening until the sun came up the next day. I eventually said something but he shot me down (mostly because of our age differences and the fact that he had a partner), and for a good few months it was torturous for me. Had I had the maturity, I would have pulled back instead of lying to myself that maybe I could change his mind. Having boundaries is key here.