Partners who can not get along with members of the other partner's family is one of the biggest reasons that couples break up or get divorced, believe it or not.
If we are lucky and grew up with a family that we love and are close to, that is a really good thing. When it can become a not so good thing is when it begins to interfere with our love life.
Some families can demand a lot of our attention and in many cases there seems that there is nothing that we can do about it. If you or your partner has a parent that is ill or aging, it can be very stressful on a relationship when it comes between you.
Those of us with a conscience will want to do what is right in a situation like that and do our best to care for our family member. This is where a partner should be as understanding as possible and if they truly love you, they understand that this kind of situation is one that you really have no control over. Couples dedicated to their relationship will usually find a way to make a problem like this a team effort.
There are also situations when we allow our families to come between us when there is no reason for it. A controlling mother or father in law can be a big problem for a couple.
If your parents, brother, sister, or even an ex spouse is causing problems, it is up to you to make sure that it is not allowed to escalate to the point where your partner has to ask you to choose between them or the other. Any partner will usually compromise up to a point before issuing this ultimatum.
If you and your partner want a relationship together that will stand the test of time, then issues like families have to be handled carefully. There can not be very much selfishness on either side.
If your family issue is one that must be dealt with through no fault of your own and your partner is unwilling to compromise, then you might need to reevaluate your partner. If you are allowing your family to interfere in your relationship unnecessarily, your partner will probably eventually reevaluate you.