Whatever you feel is valid. It's your feelings. But if you are feeling "meh" about some parts of your relationship? Could sit with it a bit and figure out what your OWN preferences are and if this is meeting your wants, needs, and limits.
Is he meeting your "time share" needs? If he is not meeting your "time share needs" then he's just not spending enough time with you to keep the thing going between you. So I could see where knowing/seeing him spend his time elsewhere could grate. Time for coffee with someone? Maybe you hoped it could be used for a good phone call or Skype visit with you.
If hearing about his other relationship up-and-down dramas drains you, it drains you. Could ask to stop being told TMI details.
If you DO want to share close details but he's just got so many people you are over-saturated with other people details? He's got more people in his poly network than you can deal with then. That doesn't mean you cannot handle poly at all. It means your saturation point is different. Could decide if this is something you want to live with as the "price of admission" to be with him or if you rather give him up and seek a more compatible polysaturation point person(s).
Is this open relationship model
a model you resonate best with? Maybe you prefer a different model? Again, doesn't mean you cannot "do" poly. Just may be that this flavor of poly isn't your style.
I agree with Opalescent. Maybe you are discovering that you dig the "closed polyfi" route more than the "poly with a side of Open" route? If so, that's fine. Everyone can like what they like.
So yeah... "normal" in the sense that dating is that time. The time to assess compatibility of the dating partner. Not all dating partners are going to be as compatible as others.
Just have to decide what YOU value most here and what YOU are after at this time. Poly comes in many flavors -- not all of them will be your cup of tea. Even within the same person -- what poly shapes they want at different ages/times of their life could change.