One of my longest titles ever, but straight to the point. Sometimes women discharge white fluid when being romantic with their partners... why? Well... turns out, it's for good reason.
Why does your girlfriend have a white discharge when you have intercourse? Because that's what's inside her before you sleep together, and if you do enough, she'll experience an orgasm and send the fluid out, or so that's what my research shows.
Obviously discharge from a penis is a totally different topic, there isn't really a home remedy for vagina discharge when it's related to sex because you know, why would you want to remedy something that isn't really a bad thing?
You should know that it shouldn't smell fishy or hurt, discharge like that may hint you have an STD (or STI). That or it could be that your hygiene just isn't up to par. Hopefully you figure it out soon.