Is my boyfriend being cold and distant or am I just overreacting?

This week the thing causing my boyfriend major stress in his family life finally came to a halt and we both had a week off of work to go on vacation to visit my family. My family loves my boyfriend and my boyfriend loves my family. Well, he has been very emotionally withdrawn the entire time and I just do not understand it. He has hardly touched me, has not told me that he loves me once, and any time that I attempt to get his attention or have a conversation he acts totally uninterested. I even mentioned to him that I was sort of feeling this way and asked if I had done anything to upset him and he said no. He has spent time around my family, but any chance he gets to slip away he does. We had a conversation about this and he denied it, saying that he is perfectly fine and normal. Then a few hours after we finished having the conversation, I was trying to talk to him once we were upstairs in our room alone but he was totally ignoring me while playing on his phone. Eventually I went over and sat next to him and just looked at him. He looked at me for a minute over his phone, just staring back at me, and then he lightly slapped me on the cheek! It was nothing hard, but it was a sharp enough that it stung a little and caught me off guard. We have been known to be playful and wrestle with each other occasionally, but that was definitely not the typical situation or mood. When I kind of opened my mouth shocked and said “why did you do that, I just wanted a kiss” he said “how was I supposed to know” and then looked away while he just puckered his lips but didn’t move, I suppose expecting me to lean in and kiss him. I said “you are kind of being an ass”, and he rolled his eyes and said kind of mean “do you have to get offended by everything”. Like WTF? He then just continued to state that he is acting totally normal and is not emotionally withdrawn and I’m just overreacting and that the slap was a “joke” and he misread the situation. Is this normal? Am I overreacting?
Is my boyfriend being cold and distant or am I just overreacting?
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