There are times when life is difficult, and some of those times are because of a partner's outlook on life. There is not one married person who was ever in complete agreement with their spouse, and they often wonder why they married at all. Those people may look at a single person's life and wonder if they would do better by leaving their marriage. The thought of leaving seems like a good idea, but that is only until they talk to someone who is still trying to find a spouse.
Single people are often looking for a good long term relationship, and many of them would like to get married. They see the help and support a good partner provides, and they want to stop making all the decisions on their own. They want to find someone with many of the same goals, and they want to build a life with that person. Either way, a lifestyle always looks better when viewed by someone not in it.