My female betta fish is acting aggressive towards my other female betta?

So I recently bought two female betta fish. (This is not the first time I have done so, a few years ago I had two females in a small bowl together and they were perfectly fine). I have a 3.5 gallon tank with several decorations with hiding places. It has been about a week and I started noticing one of them (Pearl)... show more So I recently bought two female betta fish. (This is not the first time I have done so, a few years ago I had two females in a small bowl together and they were perfectly fine). I have a 3.5 gallon tank with several decorations with hiding places. It has been about a week and I started noticing one of them (Pearl) has been chasing around the other (Ezra). Ezra is smaller than Pearl. She tends to just stay still and not move much, and she enjoys floating at the top of the tank. Pearl likes to move a lot more, and she tends to move from hiding place to hiding place, but she still goes out in the open frequently. But all of a sudden every time she sees Ezra she immediately goes after her and flares her gills and nips at her. Ezra doesn't fight back, she just swims away and hides. After a few days of this I decided to separate them and I put Pearl in a separate bowl for the time being. I understand male bettas can be aggressive, but I thought females were fine with each other. Is there a way I can have them in the same tank without Pearl attacking Ezra?
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