The old adage is, "write what you know." To add to that (and make it more of an encouragement than a rejection), we can also say, "know what you write."
Your own personal observation of people and how they interact and live really is your best tool upon which to draw for vivid, life-like characters.
You can't substitute for that with cut-out descriptions taken from the internet, and you certainly can't substitute for it by reading a psychology textbook. (I won't go into a rant here about the defects of psychology, but let's point out the obvious: most psychologists' interactions with people do not represent people from all walks of life. You're dealing with a very limited subset.)
If you want to write REAL characters, REAL stories (or realistic), and grab onto your readers with your writing, you may want to go outside of your comfort zone in talking to people.
Go and talk to some "mature women." Whatever that means. Talk to people from all walks of life—people living in the streets, people living in posh condos, wandering vagrants, people from foreign countries, people in foreign countries, anybody. See for yourself how they behave and what they do and how they speak and what they think.
It's a lot more work, but you'll wind up with your own inimitable style and viewpoint, and what's more valuable, you'll wind up with a real knowledge of people and relationships.