We have a similar situation: My girlfriend and I are not married and do not want to change that before construction begins. We will be building on a plot of land owned by her parents. The land will be transferred to her. I’m out for now, mainly for tax reasons. Mutual protection in case of separation or death will be arranged through a partnership agreement.
So far, we have been quite comfortable with this arrangement, until we had our first bank appointment this week. The bank would very much like to give us a loan, but only if we both are listed in the land register! They apparently need this as security. The bank advisor gave the impression that this is the case with all banks. Although we currently have some doubts about that... But we are going to accept it for now. Next week we have an appointment with a financial advisor. Let’s see what he says about it...