Harle is so much amazing...
harle was a creation of the 6 dragon gods, so rather than being a splinter of the Dragon God, she was merely something that was created by it. Per say, Lavos spawns were created by lavos, they cannot merge togethor to create lavos, nor did lavos split apart to create them.
its quite possible that rather than Harle herself merging with the dragons after defeating fate, she merely delivered them the frozen flame then left.
As by the fact that with only the 6 dragons without harle already look exactly like the final dragon, it isn't 100% set in stone that she merged, nor was she needed to merge.
And by that deduction, yes it is possible that when she said she didn't want to fight with you, that she meant verbally, or in a past tense rather than future tense as the final dragon
So... in my personal opinion, Harle is still out there, somewhere...
...I'm waiting for you...
Harle = the best. always.