Your feelings toward Casey's love life mirror those of most fans, I suppose lol

But, about what you said of her cheating, even though she resents her mother deeply for doing it: first, it's what you said. I think it's more complicated when societal pressure for being queer / just starting to figure things out / defining the moral borders of what constitutes cheating in her confused little mind at the time.

However, one interesting thing the show touches on is: Casie resents Elsa (her mom) and clashes with her not only due to their differences, but due to their similarities. They both want to have things their way and are extremely emotional. One of Casie's fears is becoming her mom, but since fear and desire walk hand in hand, and children (SADLY) sometimes tend to mirror the things their parents did that hurt them the most... there you have it.

In a nutshell: a complex and well written character for a complex and well written show. Enjoy the ride through seasons 3 and 4. You won't be disappointed. ^^