you and lots of others have an easy time to imagine Jesus being fully God but can't conceive that he was also fully human. I see no reason to assume Jesus was asexual. Our own thoughts of what is good or bad (masturbation) is often imposed on Jesus.

We were made to be sexual beings from the very beginning, if we have no one we can be sexual with I see nothing wring with doing it with ourselves. It can be a problem if we let it become an obsession.