There are many things you should never tolerate in a relationship, though many of these things are MUCH easier said than done. We are complex beings and while we may rationally know we should not be with someone for some reason, it is not always so easy to "just walk away." Always remember that you are a worthy being and that you never "deserve" harmful things a partner may inflict upon you; so don't forget this list of things you should never tolerate in a relationship!
Of all the things you should never tolerate in a relationship, cheating is an obvious one. Cheating should not be tolerated in a relationship for several reasons. One, if your partner is cheating, you don't know what diseases he may be picking up from others, and these could jeopardize your own health. For another, cheating breaks trust, which is a major foundation of a healthy relationship. If you happen to feel, given your particular circumstances, that working through an incident is an option you want to explore, fine, but do NOT, by any means, tolerate perpetual cheating. A cheater is not worth your own well-being.
In addition to cheating, perpetual lying should not be tolerated as trust is a key foundation in any relationship. A white lie here and there is not necessarily something to get worked up over, but if you catch your partner lying to you on a regular basis, it's time to rethink your relationship with that person.
Anger is a natural human emotion. Everyone feels angry at times, but anger and an out-of-control temper are two drastically different concepts. If you find that your partner punches holes in walls, takes his anger out on you in an inappropriate manner, makes threats, breaks things, etc., this is not a healthy expression of anger and can lead to devastating consequences in your relationship. Do not tolerate this behavior. Either insist that he seek treatment options for his temper or drop him.
Abuse of any form should not be tolerated in a relationship. Unfortunately, many people fail to recognize signs of domestic abuse for a number of reasons. You must first realize that no matter what, you NEVER deserve to be abused. If your partner hits you, beats you, rapes you (and yes, this includes marital rape), or inflicts any sort of physical violence on you, try your best to get out of the situation. I know this is often easier said than done, but realize not all men are like this and that you are worthy of someone who will treat your body with respect!
Mental and emotional abuse are often even harder to detect than physical or sexual abuse. If your partner uses manipulation, threats, belittlement, or any other means of making you feel unsafe, insecure, or bad about yourself, this is most likely a form of abuse as well. Do not tolerate a partner who makes you feel unworthy. And remember, no matter what he says to knock you down, the shame is on him, not on you.
If you find that your partner has in any way jeopardized the well-being of your children, get rid of him immediately. Whether they are his children or not, he must respect them as well as you. If your children ever say that they have been inappropriately touched, harmed physically, etc. by your partner, he MUST go. NEVER tolerate a man who harms your children.
Ultimately, all of these things can be boiled down to disrespect in some manner. If you find that your partner is not respecting your body, thoughts, emotions, etc., find someone else who will.
These are some of the things I don't feel should ever be tolerated in a relationship. What other things do you think should never be tolerated in a relationship?