Why does it seem like he changed his behaviour?

Anonymous
He is my instructor at college, so he's older and in a position of authority. It's easy to be friendly with him though. Still, he has high standards and is not easily impressed, he's not a people pleaser.

Now, I noticed behaviour from his side from the beginning which could be seen as flirting. Prolonged eye contact, smiling, giggling, staring, blushing. He even seemed a bit jealous when I was talking to another guy. He definitely was trying to impress me. I was surprised, but let it happen as I wanted to get to know him.
Because of the age difference and his position, I took my time in observing him because I needed to understand the situation first. I was thinking that he's so popular with girls anyway, that if he wanted to, he could definitely get them no matter what. Maybe I took too much time and fucked it up, I don't know. by the way, he's my instructor but my college has no policy that would forbid relationships.

Anyway, summer and some time passed, but he didn't seem to lose his intensity. He was literally still staring at me a few weeks ago, smiling, leaning in and touching my shoulders and all of that. He has said some sort of ambiguous things, created pauses where I could look at him, colame very close to me and was sweet. Now, suddenly he seems colder. It feels off. I've just now started to warm up to him emotionally, and now this.
I'm really sorry if I took too much time in getting to know him, I just didn't want to rush into anything while not knowing him enough and being in an ambiguous situation. I wasn't sure if he had a girlfriend, but recently, he mentioned his wife in front of me personally for the first time. Even though he made it seem casual, it felt weird to me and awkward. Was it him or me?
I'm literally feeling stupid and pained right now because I was really trying to communicate in a non-romantic, yet friendly way in order to get to know him without pressure. I feel unnecessarily hurt and very, very sorry. What do I do?
Why does it seem like he changed his behaviour?
1 Opinion