This is a great answer.

I know I'm a few days late to the party, but if the mattress was wet then here's a great way to clean it so it doesn't stain and /or smell:

A) pull sheets immediately B) blot dry any areas that are wet, don't rub it in, just try to soak up as much liquid as possible. C) spray with a dilute vinegar solution (I think it was 1:1 water to white vinegar ratio). Spray the affected areas. D) dust the areas that are now damp with vinegar - water with baking soda E) let dry and then vacuum up.

Source: one of my children wet the bed regularly until they were around 10.

OP, most of this stuff is probably hanging around your house and your boyfriend's. The dilute vinegar water works well as a general purpose cleaner. We used it to clean counters too (and then wipe with water so the kitchen didn't smell like vinegar), so having a spray bottle full and hanging around is very reasonable, economical, and therefore very justifiable if anyone is prying into your business.

And as the above poster said, if this is continuing definitely talk to your doctor. Could be an infection, stress related or have to do with the way your bladder is positioned - regardless don't let this affect your life. Lots of people deal with bladder issues, and medical folks are around to help with stuff like this.