It's hard to find people who will stick with you, be it a 1v1 or a group RP. But I have seen a correlation between someone's staying power and their level of friendship. That is to say the more someone genuinely likes you, the less likely they are to just bail on an RP on you. So maybe instead of looking for "Rp partners." Try looking for friends. Just find people to talk to! It might sound silly, but during the planning phase for my group RP I just chased down anyone with a Danganronpa avatar and started talking about our favorite characters, what we liked and didn't like about the game/anime, etc. I eventually started to sneak in details about my upcoming group RP, and I didn't get put off by the fact that some of them didn't think they'd have time to join. Now we have a discord, and everyone has a very strong connection with each other. 

But the trick is not to expect this to happen overnight, and not to get discouraged if the first person you decide to talk to doesn't want to be friends. I talked to many people over the course of months. That's not to say you need to talk to people for months before you RP with them, but you might.

There's a saying that goes something like "You need to be happy to find success, not have success to find happiness." No one will want to roleplay with you if you're mopey all the time. Find your mojo, get some friends, and write some stories.