5. One of you is struggling with an addiction. He's sweet. He's exciting. He loves you very much. But he loves his alcohol habit or his weekly gambling fix more. Don't fool yourself into thinking that you can change him or that your relationship will be strong enough to withstand the heartache that addiction will inevitably bring. An addict may be able to change, but he'll do so on his own terms.
6. You can't really imagine him as the father of your children. Ask yourself: Would he make a great parent? Is he financially responsible? Would he be an equal partner in your future together? If you have doubts, he's probably not the one.
7. Your long-term, non-negotiable goals in life are incompatible. You want kids; he doesn't. You go to church every week; he's an atheist. He lives in the country and doesn't want to move; you can't imagine ever leaving the city. Superficial differences can be overcome, but differences in basic values are harder to smooth over. Ask yourself: "Would I be willing to compromise on this?" If the answer is absolutely not, you may not be right for each other. The Thermostat War, And 6 More Silly Compromises
8. You don't respect each other. He puts you down in front of your friends and complains about you to his parents. You roll your eyes when he talks because there's just something about him that embarrasses you. A relationship without respect can't sustain itself.
9. You're not attracted to him. Sex is a hugely important component of a romantic relationship. If he doesn't do it for you, he's probably not your best long-term match. The Truth About Sexless Marriage
10. On paper he seems great, but you have this strange feeling... Don't ignore your gut. You may get along on a superficial level, but if your instincts are telling you he's not the one for you, listen. That little voice inside your head does not lie.