I always thought it was "you should learn to ride on an old bicycle". Or maybe that's just the dutch variety.... which would explain why neither of my coworkers seem to understand what or why I'm saying that
Usually (not always) when you're older, you value the actually relationship and can tell someone if it's not working rather than cheat when you're bored with that person. Personally, I am 29 in a relationship with a 40 year old and I've never been happier.
The german saying goes like this:
Auf alten Pferden lernt man reiten.