No matter how many romantic actions I make her do, she still doesn't get the flirty moodlet.
I try to make her woohoo and do romantic things with her wife, but the wife is the only one getting all flirty.
I don't know if it's a bug or a glitch, but she's the only sim I have that doesn't get a flirty moodlet. She stays happy, but never goes pass that when giving her romantic actions.
Even after probably, 10-15 minutes of romantic actions/queues, she doesn't get a flirty moodlet and I want both my sims to be romantic towards each other.

Perhaps you have a mod causing this. Have you removed all mods and cc and then tested the game to see if she gets flirty?
If she gets flirty then it will be a process of elimination (50/50 method) for you to figure out the faulty mod or (less likely) cc.