Real talk, the dad is the common denominator for the wife, sister, and Noah. If the daddy cheat (or have strong dealings for(they never really stated a sexual relationship)) with Noah's mom then the wife wouldn't have felt neglected nor went for revenge. She also wouldn't have created Pea Puff (I believe she started because she was recruiting old dude that she fucked in front of Noah) and hang with those old nasty ass, stank ass, filthy ass hags; she would be better than them. Noah' mom would still be kicking in with her fine ass son. The sister would have never felt tossed to the side like a rag doll if they didn't adopt Noah. She wouldn't fell like her family was a piece of shit not would she be unhappy. Also the detective type guy's sister would have still been alive.
THE DAMN DADDY DID ALL THIS SHIT, FUCK YOU SIR!
I think because Ymir loved the king so much that she could continue to follow him even though she wanted to be free. Mikasa was somewhat in the same situation as she loved Eren so much that she would do anything for him. However, with Eren’s harsh words to her and the rest of them pressuring her to do the right thing; she was able to do what Ymir couldn’t. She was able to kill Eren, basically setting herself and the others free of him. Ymir couldn’t set herself free but Mikasa could. With that being said, how the heck did she know Mikasa was the one to set her free? I don’t know and neither did Eren. Was that just a quick way to wrap up some loose? Don’t know.