Having a problem with drugs or alcohol is a pretty big deal. Suddenly, priorities are shifted around and the demon becomes all-encompassing. What she does to you suddenly takes a back seat to feeding an addiction. If you suddenly discover her problem, 9 times out of 10, it's a deal breaker. The exception is if you helped to contribute to that problem, or she developed it in some way because of you. In that case you've got an obligation to the issue you've helped create. It's a treacherous tightrope to walk, best of luck.
The granddaddy of all dating deal breakers: This is such a slap in the face to you, your trust, whatever you built in your relationship, and her integrity. When she cheats she encompasses almost every other deal breaker there is and compounds the problem. The second she's cheated there should be no second chances. If you give a second chance, you're cultivating bad behavior and inviting round after round of infidelity. Most people will cheat, or they won't. It's a binary condition and if you're girlfriend has cheated you've found yourself on the losing end of that deal. It's the No. 1 relationship deal breaker and you just need to walk away with your dignity intact.
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