I think this can all be boiled down to one thing: communication. Relationships are not difficult to maintain if you and your partner both have an actual interest in talking through your problems and, most importantly, being willing to listen and accept when you are either objectively wrong or need to compromise. There is no magic to it but it is very sad how many people do not understand this. Finding someone who also understands this seems to be the difficult part. I am so fortunate to have found mine.