I have to concur.
Get a FIRMER want, need, limit out of her.
State your want, need, limit.
GF, where we at? At this time? At this place?
I want a relationship with you. I am ok sharing you with Dude.
I need attention though, and that means regular time spent with me and in right relationship with me. Not me getting leftovers whenever handiest for you. I can make allowance for NRE, but hello? What am I? Chopped Liver? I cannot plan the rest of my life just being in the wings waiting to get feedback from you. What if I want to date others? What if I want to change jobs? What if... so tell me what times you are committed to spending with me to grow our "You + me" tier of the the polyship we share here. I can arrange my life to schedule those times to be free to be with you.
I have a limit -- if this is not the Thing any more, I need to know that clearly. Is there a Thing here any more? If yes, let's get the time management balance back to rights and grow the Thing.
If not a Thing any more, let's agree to part ways and not leave me hanging. We can be friends. But treat me nicely either way.
What are YOUR wants, needs, limits? I would like to hear your side of things.
And see what happens.