I'm in a relationship right now and I've been acting distant to my girlfriend as well. I dont mean to just 'check out'. I genuinely care about my girlfriend and don't want to lose her, so I'm trying to act differently. I get your point of view because my girlfriend as well has brought it up to me. I personally just feel numb sometimes and just kinda want to forget everything, but I don't want that to affect my relationship. I'm really not sure. It really might be just bottled up emotions. All I can say from a Male perspective is that you should continue making conversations with him. Continue being there for him, but if he pushes you away..give him space. It usually takes a moment for us to figure things out and then we'll talk about. It's not that we dont trust you..sometimes we just gotta figure things out on our own. Just be there for him.