I disagree. I think the sign that they are not good for each other is because their family values are different. Not getting along with the extended family of parents and siblings is not always a deal breaker and not necessary at all.

Without taking sides, I can understand that some people value one thing over another and here we see two people that see things differently. Neither is right or wrong but different.

Also nothing in the Op statement alludes her being controlling in fact, the OP asking what he can do to convince her is kind of implying that he wants to control her thinking, her values, her behaviors and attitudes and make them comply with his. She is standing her ground on her own values which, is not to participate. Even in a committed relationship one needs to retain their own independence of thought and values. Which is why I stated finding someone that shares his value rather than making someone that does not mold to his is the way to find a compatible mate.