Trust me, I understand how it feels when someone you RP with a lot starts to drift away to other things, but as much fun as it might be to RP with them, they have a right to move on and so do you. Sure, it might mean that- o horrors- you have to do a little work to find someone you’re compatible with, but it isn’t the end of the world, it isn’t the end of your RP (unless you want it to be) and your life will, in fact, go on. Instead of feeling betrayed and devastated, why not be happy that other people have realized how awesome your partner is and that s/he is adaptable enough to fit in elsewhere? By all means, love your partner, but don’t be creepy about it. And FFS, if there’s a problem, TALK TO THEM ABOUT IT. That’s what partners do.
As someone who has seen partners come and go, trust me. It’s far from the end of the world.