Is confession of guilt relevant?

Questioner

Before the marriage I paid a down payment of 27,000.00 euros on the purchase of a house for my son and girlfriend. Otherwise they would not have been able to arrange the mortgage. The girlfriend signed a promissory note at the notary stating that if things went wrong she would pay back 13,500.00 euros. They got married two years later in community of property and their lawyer says that they do not have to pay me back that money. But I think that if you sign a promissory note at a notary, then this has nothing to do with how a marriage is? Then a bank would never get the money back. I find it a bit strange, please give a proper answer to this.

Lawyer

The legal question is, among other things, what exactly is going on here? The following comes to mind based on the information. The acknowledgement of debt is there. But a condition (failure) is attached to the possible repayment. This creates a kind of conditional repayment obligation. - Then it could be that the condition is no longer valid. After all, they got married after two years and it didn't 'go wrong'. - An agreement/condition must be sufficiently 'certain'. This means that a condition may not be too vague. What if things 'go wrong' in 10 years because your son decides to end the relationship? Is it then reasonable that the girlfriend still has to pay? What was meant at the time by 'going wrong'? In this case, it appears to be a matter of an admission of guilt on the one hand, with a condition for repayment on the other. Comparison: Mortgage that becomes due if there is a cannabis farm in the house. As long as that does not happen, there is nothing wrong.