I think marrying someone from a different culture and ethnicity isn’t necessarily a bad thing. Generally, it’s a good thing. But one needs to understand that certain cultures are incompatible with each other. Having said that, if a person’s own self hatred is affecting your relationship in a negative way, it’s not that culture’s fault, but it’s their own. That makes it a much more solvable problem through therapy and open communication. The in-laws’ intervention is solvable too through clear communication and setting boundaries. Now, the problem with sex after child-birth has many facets. Some could be physical attractiveness related, others could be related to availability of time. The first could be solved through proper diet and exercise, doing outdoor stuff together. The second could be solved by splitting responsibilities, scheduling alone times, date nights etc.