I always bareback (have unprotected anal sex) with my partner. We are monogamous, both HIV negative and STD-free. Since my boyfriend loves to ejaculate inside me, I am wondering whether there is any health risk from the cement left in my rectum?
No, there is no particular risk of semen (cement) left in your rectum. Most of it will spill out of its own accord with your next bowel movement, if not before. The trick in your situation is to be very sure both partners are truly monogamous. This means that neither you nor your partner are enjoying a quickie here or there on the side. It's a good idea to keep communication open so you can both continue to be assured of your sexual health.
To your health,