In a marital relationship, one of the pillars is respect. Respect for partner, includes respect for the partner’s family, friends, career, likes and dislikes, opinions, values, etc. Spending time with your partner’s family and friends depends on you totally. Do you find them fun to be with? Do they listen to you and encourage you? Do you feel totally accepted by them? Do you look forward to interacting with them, spending time with them?
In case you are not really comfortable, for whatever reasons, you still need to be cordial. They are important for your partner. Maybe over time you will come to be comfortable.
Counsellor at Happy Marriages