All dating sites have effectively two sets of users: people who use it until they get a long-term partner (A), and people who can use it forever because they are unlikely or unwilling to get a long-term partner (B). That is effectively intrinsic to the activity they are born to serve (dating). This said, there are enough people belonging to the B set to keep them in business pretty much forever.

There is also the option to provide ramps for people in A towards some other form of socialization (double dates? dinner parties?), but I don't think anyone really tried it yet.