Does a promise ring have anything to do with a church or not?

Just have sex with her already.

In short, NO. There is no scriptural support to a promise ring

Promise rings allegedly date back to the 16th century. One illustration, dating from 1576, might be showing a promise ring being given, demonstrating that the tradition could have existed at that early date. In those days, when a man could not afford to get married, he would often give his intended bride a promise ring as a placeholder until marriage became possible. However, there is nothing concrete to show when the tradition started.

All in all, a promise ring is a tradition (ref: wikipedia)

If you would like to read more about what the bible says about Marriage, here is an online library which deals specifically with what the bible says and the history of Marriage, setting religion and tradition aside

I hope that helps

Marriage:~

http://wol.jw.org/en/wol/d/r1/lp-e/1200002912