This is what I like to call a sticky wicket, both because it is a pretty accurate description and because it usually makes my colleagues laugh and lightens the mood so we can think outside of the box for a bit.
I definitely see an opportunity for some fundraising and community awareness building. It’s basically an if-then situation. If the public sees the value of the bench, then they will want to make contributions to see it conserved and protected properly.
May I suggest looking at a shelter for the bench? Perhaps something with clear sides to discourage romantic encounters and some signage about the need for conservation treatment. This would not do anything irreversible to the object itself but may stave off further damage until a more permanent solution can be funded.
Hope you can be successful!