Is it normal for a man to pretend to have feelings you?

So I met this guy in one of my classes and we gradually became friends. It seemed that he was attracted to me (he was checking me out, staring at me for way too long, getting nervous around me, standing very close to me when speaking, etc). I ignored this for a month or two, but then slowly began to develop a crush on him. We began flirting, but when the flirting became too intense, I backed out. Interestingly, he stopped flirting in a sexually overt way and instead began to treat me very gently. He paid attention to our conversations, listened to me closely, constantly watched my reactions to everything, valued my opinions- overall, he seemed really interested in me. It seemed to me that he was infatuated and I kept expecting him to make a move, but he never did. By this point, I had a big crush on him and on the day that I was planning on asking him out on a date, he shows up to class with none other than his GIRLFRIEND. I was shocked. I didn't know he had a girlfriend (they have been together for several years).