Originally Posted by Syl
They have told me themselves on a few occasions that they wanted multiple lovers because they don't want to feel alone ever. They also seem to want person #2 and/or #3 in general and not like a specific person ie John or Jane.
Isn't polyamorous wanting to be with other people because you love them as a person because you actually know them and want them, not because you want to use them so you don't feel lonely?
I'm afraid that from solely what you wrote here, yes, your lover is using poly as a crutch. (I'm well aware that there is always the other person's point of view.) Poly can't fix lonely. People that desperate not to be alone do not want to be with themselves - ever. They would do anything not to face themselves. Unless your lover begins to address whatever the problems might be, your lover will always want more and more people in their life. They will always be that lonely person in the middle of crowd.
Your instincts are telling you loud and clear that this relationship, as it is now, is badly damaged and likely doomed. Perhaps you and your lover can agree that you will support them in therapy or whatever else might help. But you can't fix this by yourself and deep down, you know that. Only your lover can do that. I do not mean to imply that your lover is bad or selfish but it really sounds like they have lots of work to do on themselves before they are ready for any relationship, much less poly relationships. That's really what your 20s are for -discover who you are and make your peace with that. (It's also why your 20s can really suck ass.)
Your instincts are just fine. Listen to them.