Some people want people they like, to get along with each other, they take measures to make sure that everyone they hang out with like each other back. For example your friend might want you to get along well with her husband and kids, or your partner would like it if you got along with her family, your family would prefer it if you got along with all your relatives, your relatives would be elated if you got along with all their relatives, may be that's bit of a stretch but you get the gist.
I understand that it can be very stressful mentally to be spending time with people you don't get along with - simply in the name of association.
I am totally fine if two people I am extremely fond of, are not fond of each other much. The least I expect from people in general is to be civil and well-mannered no matter who they are and whom they like (or not). I have no need for my girlfriend to get along perfectly well with another girlfriend, or every family member to get along with every other family member, so on and so forth. It is great if they do, but if they don't it doesn't bother me.
It also does not bother me if someone I am fond of is hanging out with someone I don't get along with. I really don't care to indulge in anyone's personal dynamics with each other. I like giving people their space and letting them make their own choices about who they want in their lives and/or don't, my wavelength matching or not matching with someone does not imply it will for you. I do not think having me as a common link should be a punishment for anyone. The only relationship they need to care about is with me. Anything else is not necessarily my concern.