I won't sugar coat it. It is partially your fault. But honestly? We kinda all share the blame. But this is her RP. She should have taken extra precautions in case something like this happened. Although she did outline certain 'side quests/stories' to give a guideline, even if you did pick it up I have a feeling it would stall eventually. Maybe I'm wrong on that, but I do know everyone is partially to blame. Perhaps the real interest wasn't there? Wait, not perhaps. It is. If everyone was completely interested and dedicated and motivated, it would have lasted longer.
I wouldn't worry about it too much though. Life gets in the way, it's understandable.
If I was running a rp or planning to, I'd probably look into months of planning, and set up A, B, C, etc., and set up scenarios and what ifs and how to solve them to keep it alive. If it turns out I have too much drama in my life or something is heating up, I wouldn't even touch the idea and drop it. I'd run in the other direction.
I don't know EXACTLY what happened, nor does anyone for that matter. RP's come and go though. Hopefully any other RP's I'm in will come to life. Otherwise.. Yeah I got nothing. Probably find new stomping ground somewhere (though I'd still be here obviously
)
Try not to let it get to you. This happens all the time. It's like (ironically) a skyrim playthrough. You get pumped for this new badass character, only to find out 10+ levels later you catch yourself saying aloud...
"I'm bored."
Maybe THAT'S what happened here.