magpie, almost40, says: How can you trust someone when they keep lying to you? Is it not cheating when you interact with someone you don't know? When they do it behind your back. I'm very angry and upset, need to vent, need someone I can trust. My brain says one thing but my heart says another. What do I do?

VictorM's advice: Is he cheating? It's important for you to understand how guys think. As youth erodes around us (guys know because we start growing ear and nose hair -- I know, yuck) there is a desire to hang on to youth. One of the many ways of doing that is feeling attractive to other women, usually younger women. Many guys flirt to fulfill that illusion. So is your guy carrying-on with the intention to follow-up on the interaction or is he simply satisfying his need to feel attractive? The difference between the two is a key differentiator between cheating and daydreaming. So, is he fooling you or fooling himself?

But anyway, going back to your very first question, you can't trust anyone who keeps lying to you. And that makes any relationship hell because you're always hearing a lie even when it's the truth or a fantasy.

The brain and the heart can work together. Take a step back and give it a shot.