Using bathroom and semen falling out after sex..

I was wondering if when you use the restroom after having intercourse with your partner does cum ever come out of your body? This almost always happens and my partner's semen is thick. I don't know if that could explain why after being off of birth control for a little over a year now that I haven't fallen pregnant. It just makes me wonder why this happens. Anyone have any ideas as to why this happens and does it happen to anyone else? Picture below.