Okay, I need some tips...

Under an array of "perfect storm" circumstances my boyfriend nearly always finishes inside of me, which I of course have no problems with. He loves it, I love it, and in the moment it makes much less of a mess. My issue, however is the notion of what goes up must come down. We'll get done, wipe down, and go to sleep. Then the next morning after I've been up and about for a bit (often after I go to work) it all just comes out, sometimes all at once sometimes in spurts. Maybe I'm doing something wrong or maybe this is just how it goes, but I was wondering if anyone had any tips for managing this. Any advice from personal experience?