When you accept something that's less than what you hoped for, that's called "settling for" something.
For example, if you want to drink some coffee, but there's no coffee left, you might "settle for" tea.
We sometimes use the phrase "settle for ___" to talk about marriage or dating. People sometimes settle for a partner who isn't as attractive, as rich, as intelligent, or as kind as they would have wished.
I'm holding out for the right person. I'm not just going to settle for someone because I hit a certain age.