The things you guys fear is real. There is a very real chance of rejection. And the pain and disappointment is real. And even if you marry her, there is always a chance of divorce.
However you do not need to fear. Because God is indeed with you. =)
If you never talked to you wife, you would never have married her. And your will never have those beautiful children. And you will never watch them grow up.
It is same as talking to non-believers about Jesus. Yes 99% of them will laugh at you or be mad at you, and they walk off. However if you never talk to any non-believers, how would you ever found that 1% that will come to faith because of you? If you never try you will always be at zero.
Now you got to use common sense and discern the lady. Is she a Christian? Is she a good fit for you? etc. However if you really want a GF, the only way is to go for it.
If you don't really want a GF, then yes you can sit back and do nothing. But you should be aware of your choice. So at least you won't regret, because hey you made that choice.