Hi, my boyfriend can cum while he masterbates, but can t while we have sexual intercourse with me. When we are done having sex, his testicles get swolen...I think it s because of semin build up. He has came twice before, but we have sex often and I know it s not me. He does have lower back pain and neck problems, so maybe that has something to do with it. I am really curious to find out what the problem is. Any advice?