What do you think about Cohabitation Agreements before letting a Girlfriend move in?

It's always a good idea to discuss these things and make agreements before moving in together. Many people don't, and then they wonder why everything is allfucked up in the household.

There's no such thing as a prenuptial agreement for single people, by the way. Nuptial = marriage

Nothing wrong with that idea at all. Roommates of all sorts have agreements, sometimes written, sometimes not. It make sense to me! If it is to be a successful pairing.. there need be room to alter or negotiate as time goes on though. Most of us are not really very good at predicting the future. Agreements are great. Solidly carved in stone? Not so.

It's the best thing since sliced bread. If they don't agree with a signed paper that explains who pays/does for whom, you still have proof if it ever has to go to the courts. And someone who won't sign probably wouldn't make a good neighbor.

Good fences make good neighbors.

Sharing a home with somebody is what we oldsters used to call "a heavy trip," even when that person is just a roomie, not a sweetheart. Having mutual agreed upon "Rules Of The Home" is a good way to avoid unpleasantness. Before anybody starts bringing their stuff over, there needs to be agree on stuff like:

Do I need to get your OK before I bring people over?

What need to be done with dirty dishes and when?

Is it reasonable to tie up the bathroom, rather than using some other place, for hair styling, make up, etc?

Do I need to check with you to make plans that don't include you, like working on Saturday or having dinner with my mom?

What need be done with dirty laundry and when?

How are the housecleaning, maintenance, and errand running chores to be divided?

And so on.

And yes, of course that agreement includes the money stuff, rent, utilities, cost of cleaning products, shared groceries.

And you should both be clear about "dates." If you two go out for dinner, who pays?

Even when there are no real assets involved, sharing a home can be challenging and roomies should prepare ahead of time for that challenge