That is mistake #1.

Do not fall in love with a rolling piece of metal. It has all kinds of things wrong with it and you are setting yourself up for disappointment. Furthermore, you are setting yourself up for overpayment. Decide, right now, what is a fair price for the vehicle and do not exceed it.

Did you go over the vehicle yourself and check on all the items mentioned above? What doesn't work? How's the front suspension? How's the transmission?

Don't consider marriage until you know what you are getting into.