While we would like them to read our minds, they can't. And it might be frustrating for him bc he probably feels the tension but has no clue how to bring it up, what is wrong etc..... You just need to spell it out for him. It doesn't sound like he is intentionally ignoring you but seems to be just........oblivious. My favorite is the letter. If it's hard for you to say aloud but you want him to know how you're feeling, write it all down and give it to him. Leave him the letter so he can read it alone and give him some time to process it. I'm sure he will probably feel bad for not noticing these hints in the first place and will want to at least try and support you. I hope you two can figure this out!