There are as many reasons that relationships fail as there are failed relationships but some relationship issues don’t have to be fatal. If they can’t be avoided, (they’re already happening) they may simply need to be addressed so that behaviors can change.

Non-Acceptance
You meet someone and think, “He’s great, but…” We’ve all done it. We find someone that we like who has many qualities that we really dig but there are some things about them that are kind of a turn off. We weigh the good against the bad and decide if we want to go any further. Deciding to over look a partners personality traits or behaviors that we find annoying is fine as long as we commit to acceptance. The problem is that more often than not, we don’t. We go in to it thinking that we can change them. We believe that once they see how great life can be with us, they’ll change for us. In most cases, they won’t.
Over time we get frustrated with our partners and either demand that they change or use passive aggressive ploys to elicit a modification from them. We may even make insensitive comments about them or worse, point out their flaws to others in an attempt to shame them into complying with our will. These doesn’t work. They may even agree to make changes but, depending on the issue, the changes are unlikely to stick. They may grow to resent us for our overbearing behavior.
How do you avoid this pitfall? There are two ways. First, talk about these things before getting serious. Some things need to be ironed out ahead of time. For example; if your partner isn’t ambitious and works a low paying job that they love but you expect them to foot half the living expenses when they move in, you can’t just assume that they’ll leave their great job for a higher paycheck. Let’s say that you believe your partner spends too much time out with the boys. If you’ve accepted this behavior when you were dating, they are likely to expect you to accept it when things get more serious.
Second, simply accept your differences. You picked him and for better or worse, if you value him, you need to let him be himself, no matter how flawed you think they may be.
Lack of Trust
The only things as bad as wondering if your partner is unfaithful is being accused of being unfaithful when you’re not. If your trust issues are justified, forgive or run for the hills but if the lack is trust is manifesting without justification, you need to find out where your trust issues are coming from. We carry our baggage from one relationship to the next and it’s unfair to our partners. I was once told, “You carry the burden of proving that you’re better than every woman who came before you.” but that shouldn’t be the case.
If you find yourself cracking the lock code on his phone while he’s sleeping or sniffing his laundry for left over perfume when there have been no signs that he’s been cheating, you probably have trust issues that you need to address. If you don’t, they’ll cause you to do “Crazy Ex” things until he leaves you.
Differing Priorities
For some, a romantic relationship is the most important aspect of their lives. For others, it’s just a part of the equation and things like family, work, friends, or a hobby hold equal or greater value. If one partner expects to be the center of the universe while the other wants to spend a large part of their life apart from their partner, one will end up with hurt feelings while the other feels smothered.
Relationship building is like building a fire. If you just toss a bunch of logs on the fire without leaving room for air circulation, your fire won’t burn. If you’re relationship can’t breath, you also run the risk of losing the flame.
If there is trust in a relationship, there is no reason why partners can’t have aspects of their lives that they keep separate from the relationship.
Communication
I saved communication for last because it’s a pivotal part of the other three. Proper communication helps to avoid most pitfalls in relationships. If you communicate your expectations in the beginning, your partner can decide if they’re willing to change for you. If you communicate rather than being passive aggressive your partner is more likely to hear you. You can’t just assume that you hold a place of importance in someone’s life. You need to know where they see your relationship going. If you’re uncomfortable speaking honestly with your partner, you need t evaluate the situation and determine if it’s a problem on your end or not. If you are justifiably worried that communicating with your partner will make them angry, you may be dealing with a gas lighter or narcissist and it may be time to move on.