Well, that's her decision and it's cool with me. If she doesn't want to cut weight or doesn't think she can, then good for her for wanting to leave.
There are more female MMA established organizations for her to go fight at, with more competition and variety. The UFC female "division" will be gone within a year or two from lack of interest/draw and no fighters, so honestly it's not as if Ronda/Cyborg won't ever fight, they will meet in a different promotion down the line I'm sure.
“Anna, my strong, terrifying Anna.” -Cas
"You lack the requisite spine and testicular fortitude to study under me" -Elodin