In some episodes (the good Garnet episodes) she is a third entity in Pool Hopping she has insecurities about being the leader and feeling inadequate now that her abilities don´t seem to work as well as they did before. In future vision she shows fears knowing all the ways Steven can get hurt. those feel like Garnets problems.
My problem with R&S is that they are one note and by association they make Garnet one note half of the time, imagine if instead of a fusion they where just a couple, all their interactions with everything boils down to "how does this affects us as couple" there is not much to them outside of that. Ruby is emotional and dumb and Saphire is cold and collected their characters end there.
The closest we actually see any of them being something more that an extension of each other is the episode where Ruby wants to be on her own for the first time in her life, and the episode pretty much end with the idea that she enjoys being part of the relationship.
I really wish if Garnet could be a little more like Sugilite and try to stay form against what R&S wishes.