I have had this problem as well. I can get there on my own, but when it comes to my husband doing things it just does not work. Then I went a week without masturbating and when I felt ready, my husband helped me while I did things myself and we took it really slow. I felt like the pressure to succeed wasn't there and I could just enjoy myself. But I got there. For the first time in like a year with his help. Sometimes you just have to take it slow and not get so worked up about it all. Slow and steady wins the race.