It can be a challenge to be in a relationship. We do not always agree and we often have different values. It could be that he is all for hi-tech interior and she is for old fashion. Maybe she values spending time together and he is completely absorbed by his carreer. Perhaps he wants children but she wants to wait, or not have any at all.
Raising children is a subject which can put relationship through a tough test. It's not easy to come to agreement about how we are with our children. Can they eat candy every day or must they have a fixed day for eating sweets? Can they eat with their fingers or must they use knife and fork? Are they allowed to watch Tom and Jerry or shall we play UNO?
There is also the issue regarding friends. Something, which can produce discussions in a relationship, is the question about how much time should be used on the friends. Is it ok for him to go out on a boy's night dringking till dawn? Is it ok for her to go on a week's holiday to Crete with the girlfriends?
And then there's the family. Yes, that can give great conflicts between the two. Of course. We love our own family. That's the one we have come from and the one we turn to when something goes wrong. However our partner does not have the same relationship to your family as you have. Your family will most often take your side in a serious conflict. They will be on your side. And your partner knows this.
There can be many more challenges in a relationship than mentioned here. Most likely the greatest challenge for woman and man relationships is sex. There are a lot of women who do not feel like having sex - that often, not as often as the man. And that can create conflicts in the relationship. Many things can be done to solve this and it depends on the underlying reasons for the lacking lust. More about this here. (Link to lust).
If there are children in the relationship you should stay together. This does not mean to stay together at any price. However an effort should be made to better the relationship.