Do you masturbate?

So I'm talking with a young, cute boy and he wants me to cam with him so he can "get me off". I've tried explaining to him that I don't like to masturbate because I can't get myself to climax and it's extremely upsetting. When I try, I usually just get frustrated and then end up crying so I just don't bother. Just talking about it is making me cry. He says stuff like "I believe you can, just relax and focus on your breathing, I want to help you." But I've tried many many many times. I can get the big O super easy when I'm intimate with another person but not by myself. Does anyone else experience this frustration??? How does it affect your long distance relationships??