Can I trust him? Is she cheating on me? Can I believe the things they are telling me? Trusting someone is a complicated thing. And it’s very difficult to rebuild once it’s lost. One of the things you have to ask yourself is, what do I mean? Can I trust him/her to do what? Sometimes couples haven’t really spelled out what they expect from one another. In this instance, it’s best to think about what you really want, and ask for it a nonthreatening way, without making any accusations.
Unfortunately, people do lie. People lie for many reasons and not always for reasons that seem obvious to you. And again, unfortunately, some people are quite good at lying. So this is another time when it’s important to pay attention to your feelings and get more information.