"Human relationships and expectations have evolved a lot in the last decade"
Is this really true? I agree they've changed some, but a lot?
In any case, I'll take a stab at your question. Not thinking about how to make money, just how to make something successful from the users' point of view.
I really enjoyed OKCupid in its heyday, circa 2010. I only got a few dates out of it, but the site was genuinely fun. Profiles were long, with multiple essays, and this was very much encouraged. The personality tests were also fun -- and the founders discovered that questions like "Do you enjoy horror movies?", "Have you ever been to another country by yourself?", and even "Do you like the taste of beer?" predicted compatibility much better than trite questions. There was no notion of a "match", messaging worked like email and you could write to anyone on the site.
As the founders said, "OKCupid does a fantastic job at matching you with people who claim to be what you claim to want." I loved the tongue-in-cheek humor and the site's awareness of its own limitations. And you had to put in a little bit of effort to use the site, which was very much a good thing.
OKCupid still exists, but it's a shadow of its former self nowadays.
How to improve? Maybe a slight barrier to engagement, such as a few tailored questions you have to answer for each person before messaging someone. (To prevent men from sending out messages to every women in sight. Or at least make it more difficult...)
Or, something like, if you look at a profile, then you can't navigate away for at least twenty seconds. Again, to prevent you from messaging too many people, or dismissing lots of people instantly.
I believe that the biggest issue with dating sites is that it's hard to align the incentives of the user with the incentive of the site owner. Not sure how you solve that one.
