Me (32M) and my wife (31F) have been together for about 6 years. We get along wonderfully and through everything, have never had any major fights except for one thing.
I personally feel like my wife makes no effort to get along with my friends.
Now to give context, all my friends and I went to the same university for undergrad (3 guys and 3 girls that are married). My wife is the only one that did not have this common trait of attending undergrad between the 8 of us, which is really not a big deal if you ask me.
Early on in our relationship, my friends would always try and be friendly to her and talk to her when we would mutually hang out. My wife was cordial, but you could tell that she was uncomfortable. I would speak with her about this, and she would always comment that she was an “outsider” to all of us.