It is theoretically possible to make 'repeat business' on long-term reputation attracting new customers, similar to how schools and universities can thrive despite only ever serving a customer once. However, how often will someone need to introduce others to a dating app? A multi-year timeline for word-of-mouth is probably too much for a VC funded app.
There exists dating businesses that can profit from long-term relationships, its called Church (Marry at a church = lifetime donor + children likely become members too), hence churches are far more optimized and effective at building long term relationships than apps could possibly be.