Here is a list of things that can truly sabotage a marriage. Some of these things might not seem like they can cause damage in a relationship right away, but sooner or later they do begin to affect. If you find yourself doing any of these things, find a way to fix the problem before you need a lawyer.
Thinking only about yourself, your needs, desires, and issues can cause problems. Once you get married, the "I" becomes a "We." Be considerate of the other person's needs, wants, and feelings. When in doubt, ask, and never assume that you already know the answers to those questions.
Hurt can quickly turn to anger, and anger can turn to bitterness just as fast. Work through the hurt and anger and forgive them. Being angry under the surface will only hurt you more in the end.
If you are doing something with someone else that you know your partner would not like, you are cheating and you need to stop immediately.
Also, with some decisions you can opt for something that you both can agree on, or work things out so that both of you get your way.
Don't make the mistake of making major financial decisions without them (anything more than USD 500 is major unless you are both making money in six figures or have no debts and plenty of savings).
It is important to connect emotionally, spiritually, and physically because that enhances the entire experience.
Your confidence in yourself and your expressed trust in your spouse will make you more attractive to them. Always give them the benefit of doubt unless there is reasonable suspicion. The fact that you don't think you're good enough probably isn't a reasonable suspicion.
Remember why you married your spouse, and trust that they will give you more of what you want than anyone else. That other person might seem like everything, but that is only because they offer one or two things that your spouse doesn't. In the end, it is not a good deal to settle for two things that you want and sacrifice the things that you already have.
Those are the ten marriage killers. Try to steer clear of them, and your marriage will probably be good. Not perfect, but good.