Might be a bit late responding, but I did the exact same in my first playthrough and it absolutely can lock you out of further areas. To be clear, you do not have to make the slime girl sad to progress, but you will be doing an interesting jumping puzzle to open the next area(s).
The STRAT:
In the hivelands there is a stone bridge that leads up to the neko area. On the stairway up to that bridge, on your left, is a ruined set of columns that you can jump onto with a little skill. Once up there, you carefully skyrim your way over the mountain and around the edge all the way to the inside of the gate that leads to the pleasure pastures. At this point you can hop around the invisible wall and walk into the pleasure pastures without the key, at which point you can speak to the dryad and complete the quest. Saving, then reloading will teleport you back to your farm so you can complete the quest and get the queen bee's key. I would suggest using that key to unlock pleasure pastures, then the key from the dryad's quest to unlock the way down to the sea so you can retrieve the key from the slimegirl, as using that key on the neko area will require a much more irritating jumping puzzle to fix (from the same starting bridge, but on the other side working your way down to the bottom of the canyon).
Don't fall too far or slide down the geometry, as that will kill you and you will need to start over. I recommend making friends with the death shrine right there, as it will likely take a couple of tries.
I won't pretend that figuring that all out wasn't fun, but executing it definitely wasn't. Best of luck to your quests for happy slime friends.