beta
Let me tell you one thing.
MC transmigrated first and as the villain's close family. He literally spent all his life with her. The bond between them is big.
Sister played the game, so it's natural she doesn't like villain. And she spent very little time compared to her brother and of all, beside the female lead. So, her stranger-ness to villain is natural. And she attraction to female lead is big and wants to see her in love harem is bigger.
And if u get transmigrated into a game, reaching the end is the most possible solution.
She is doing what a normal person would do from her place.
There's nothing wrong with her.