Infidelity is one of those things that can easily kill a relationship. This is true whether the infidelity is emotional. People cheat for many different reasons that don't always have to do with liking or being interested in someone else, and sometimes, depending on the situation, relationships can handle the occasional wandering eye.
When someone hurts you physically or makes you feel bad about yourself on purpose, it's clear that it's time to end the relationship. Unfortunately, I've seen a lot of couples who don't realise that they bring out the worst in each other, and their fights often get worse until they do damage that can't be fixed.
Most of us would leave if we found out a big lie was a lie (like finding out he has a wife or girlfriend), but what about all the little white lies? The small lies can sometimes cause more trouble than the big ones. If he lies about how much he makes or doesn't tell you that his best friend used to be his bed partner before you came along, you might realise that you don't really know the man you're falling for.
One of my ex-boyfriends said that I didn't care about how he felt. He said that I often didn't care about his problems because I didn't think they were important. Once I got over myself, I saw that he was right. Disrespect can be obvious, like when a man calls you by your name or flirts with other women in front of you.
One of the main reasons why people get into relationships is for companionship and support. So what's the point of being in one where your partner is condescending, critical, and doesn't defend you or your actions? Shoot, there are enemies who will at least tell you WHY you might want to rethink questionable actions instead of just putting you down.
Have you ever wondered if you really listen well? Do you talk about your needs and worries in a relationship in the right way? Without good communication, relationships can fall apart quickly. Too often, partners think that their partner should "just know" how they feel, so they don't have to say it. I'm sure you've seen at least one couple in your life that didn't know how to talk like adults.
Don't think that reliable is the same as predictable. The older I get, the more I think that the best relationships are steady and have some sort of routine. People find it funny when two people are always at each other's throats and then end up in each other's pants.