When a girls goes on a trip with you, she’s taking time off of a work and family schedule to be with you. So no, it doesn’t mean she owes you anything or is being selfish. Plus you guys went dutch. You wanted a trip away and you wanted company and did the inviting. So she was doing you the favor of accompanying you. I think it showed that she was a good sport by paying for meals. Periods are not 100 percent predictable.. A lot of women have painful cramps and fatigue too. She was not being selfish. Plus - there are tons of guys that are ok with period sex (I’m shocked by this too- but trust me a lot are). So she could say your being selfish too.
Now with a FWB situation, I guess it depends on what else is available to you as to whether you want to keep seeing her. Those situations are more about being selfish anyway. They are not about giving and reciprocal relationships. They are about getting your needs met without having to invest - so why would you expect more from her?
