Not being sexually compatible can be an issue. I hope you guys come to some agreement. I know if the committment is there, you both will make an effort to develop a 'sexual agenda' that works for you.
What I would say is ... there is no sex that is safe. Whether your bf meets a stranger for protected sex, goes to a party for protected sex, or deals with partners for protected/unprotected sex ... there is always risk. I don't mean to freak you out but protection is not 100% and there are some things protection may not cover like crabs or herpes. Even with sharing sexual health papers, some diseases (one in particular-herpes) are not included unless they are actual signs of this disease present on the body during examination for testing. I spent years working in clinics and with organizations focusing on STDS & HIV/AIDS and have been involved with people (on various levels) who were positive for one thing or another. With that said, you will always have to proceed with caution with anyone.