Traditional wedding vows may state that somebody is going to stay with their spouse for richer or poorer, but they do not go into detail about how a person may deal with their partner experiencing a change in financial fortunes. Money is one of the most important things for a couple to be on the same page about, and when finances get tough, there is every chance that the relationship will as well. Even well-adjusted couples have money arguments from time to time.
How expenses are split between two people is an issue that often plagues modern relationships. A lot of people would argue that if both are working and earning similar amounts, it makes sense to try to pay for things equally, but life isn't always that simple. There are situations where one person feels the need to step in for the sake of the other, and conversely, there are also scenarios where they may do all they can to get out of paying a particular sum. Marrying somebody who is financially irresponsible can make you lose sympathy for any money woes they may have.
Ultimately, the best kinds of relationships are often those where both partners are consistently generous to one another, whether that is monetarily or otherwise. Although somebody may have legitimate reasons for not wanting to pay for something, there are instances where that can leave their spouse feeling uncared for, and wondering about the validity of the partnership that they have opted into.