Her age, whether or not she’s married and whether or not she has kids is completely irrelevant.
Demanding an apology from someone is immature, but is there something you should apologize for? If you don’t believe you have anything to apologize for, is there anything you can do to help heal your relationship?
If the two of you had an argument, don’t forget that one of the biggest mistakes people making is forgetting what it really means to “win.” Causing the other person pain and forcing them to admit they are wrong is not a win. A true win is finding a way to come back together in the end - to stop being upset with each other - to truly listen to each other, consider each other’s perspectives and grow closer together through better understanding and mutual respect. Not every argument ends that way, but that would be a true win.