Help! Broken bond! Fighting rabbits! (and cute story)

Okay so I have 4 rabbits however the 2 I'm having the problems with are buttercup (approx age 3-4) and blossom (approx age 1. 5) this is kind of a hilarious story because up until about August I only had 3 rabbits and 2 and we're well bonded for awhile and when I brought in #3 (buttercup) they both hated her so she ended up being a free range bun because she's so well behaved...

One day she got lonely so she went into my bedroom (I have a huge stuffed animal collection) and she picked out an animal about her size (a cat which is holding a heart that says "I love you" apparently buttercup likes the hopeless romantic type haha) and starts licking it and dragging it around the house cuddling with it and of course then the humping started.... She seemed to honestly think it was real, if I took it away she would get very upset.

So in August we brought in Blossom. It only took a few days and those two were inseparable. Once the new bun was on the scene she ignored Stuffy (yes we had to name the stuffed animal) up until about 2 weeks ago then all of a sudden she starts humping Stuffy again which I found odd but thought oh well. Few days later I noticed buttercup started to nip blossom and kept finding bunches of fur all over the floor. She's not fighting to the death or anything but she's definitely not being nice and the last few days I've had to put blossom in her cage while I'm gone for her own good. I was about to start switching them so maybe being around the others smell might help but I don't know! I'm not very experienced in rabbit stuff I've just been very lucky bonding up until now. I could use some advice!
Poor blossom is definitely upset she keeps being rejected

Are both Buttercup and Blossom spayed? You mentioned Blossom's cage - does she have her own cage separate from Buttercup? Do they share a cage? Normally, bonded bunnies must remain together 24/7. They can't be separated. Could you describe how often they have been together or if they are ever separated?

Neither bun has been spayed.
Until the fighting they were both free but they spent 99% of their time together cuddling and ripping apart cardboard boxes in the bedroom with an occasional adventure out in the living room.
As of right now I have a decent sized cage in the bedroom where I'm keeping blossom to make sure they don't get in a huge fight when I'm gone. But they're still sniffing each other through the wire.
Also they do get along for short periods of time, so it's not like instant fighting when they see each other. But it's too bad to leave them alone for long. The room will be covered in fur chunks if left alone for 4 hours or more

Are the approximate ages in years or months? I assumed years, but just making sure.

Sounds like hormone-driven behavior to me. It's really hard to get unneutered/spayed rabbits to get along, mostly because hormones can make them tetchy (the occasional false-pregnancy doesn't help either, might be what's happening here). Sometimes, rabbits don't get along because they plain hate each other (or hate rabbits in general, I've known a doe who really hated the guts of any other rabbit alive) but it doesn't seem to be the case here. I would advise to try spaying, if anything it will prevent uterine cancer and false pregnancy issues in the future. It doesn't work the same for every rabbit, from what I've read, but every rabbit I've own became much much calmer and nicer toward other rabbits after spaying/neutering.

Intact rabbits do have a higher tendency to lose their bond.

Can I ask the obvious question, are you 100% certain that they're both female?

It's probably just hormones getting in the way of things, they can fluctuate a bit and even a false pregnancy can lead to broken bonds.

First thing I did with both buns was take them to a vet to get checked over and sexed so unless the vet messed up they are indeed both girls. I have an appointment for my aggressive little buttercup to get spayed next Tuesday. How should I introduce the pair again when the surgery is done? Any way in particular?