Explain the game to the user and make a package where the company reserves a large-ish sum on the credit card and they get to cash only when the user stops dating after a successful match.
The dating app doesn't make any money until a successful long-term. The dating app could also require feedback after dates, to both improve matching and verify that one user is not cheating.
If a couple colludes after they get i long-term relationship, they could continue dating... but it increases risks of cheating.
This aligns the interest of the daters and the dating company (less infrastructure expenses and also less risks from reserved but unpaid transactions).
There are open relationships, the app can learn to screen for people with profiles that are prone to that and avoid making the escrow offer.