The similarities of them are more then you think, especially knowing that their relationships is a toxic one.

the red equal sign indicates opaline and gothel being the gaslighters, where as the green ones shows misty and rapunzel being the victims of their own gaslighter there.

And yes I know that the relationship between misty and opaline isn't as toxic as the other two there, yet please think about it, you'll see that opaline is just using her to get what she wants, which is the magic that she thinks is rightfully hers, just like how gothel is using rapunzel to stay young with her own hair.

And yeah, they both gaslight them into thinking that everyone except their "mother figure" would not care about their well-being, and that they're the only "friend" they have, which is a pure lie there for sure.