i'm muslim. I'm married. To me marriage is such a gamble.
You dont know your partner until you stay together under the same roof with her/him.
Besides, during the marriage many life test as an adult that happen, no money, getting fired, in law conflict issue, sickness and etc. It is difference how a married couple and love couple handle the difficult situation. During couple phase all is happy and lovey dovey stuff. After marriage your partner tend to show their true colour.

I dont understand what is the purpose of non-muslim to get married. you can stay together and can test drive some more. if you want to get married be ready all mentally, physically and emotionally. it is long term commitment and not all success until the end.