I used to be the group social planner for my friends and went through similar resentful type feelings. It hurt and made me feel lonely and left out. I didn't really admit to them how it made me feel. Instead, I sent a message that I missed them but was out of ideas of something to plan. I asked them what ideas they had to get together.
That was the best thing I could have done. One admitted to having some financial issues and going out often was rough. My other friend was going through some family drama she was afraid would be a burden to us. By opening up a little about missing them and asking them what they would like, we got closer and more understanding with each other. The resentful suspicious feelings I was having were real, but were an invention of my anxiety and not what was really happening in my friend's lives.
I don't think you have anything to lose by asking them what they want to do. Sometimes what we imagine is going on is not what is real. You won't know what is true if you don't speak up.