I love watching their face for another reason - I like to see them in a little bit of pain and watch their facial expressions while being anally fucked
Dont give up. Ask your man to go slow, use lube, relax, and think about how much pleasure you are giving him. Its a very strong thing for a guy to have. Dont let that fact be lost on you. Keep trying and eventually you'll be able to let him have your ass without much difficulty