
Well, we always knew Jean was crushing on Mikasa, but she never returned his feelings. The ending indicates that Mikasa is choosing to live free like Eren wanted her to do, but holding onto her feelings for him (by choice), which is actually what Eren secretly wanted. It's a bittersweet ending for them both.

I think Jean just hoped he would end up marrying her since he had a crush on her, but I don't think it will ever happen. I also think that the fact that Jean was talking about other women in the final chapter really showcases that he has let go of Mikasa (probably because he realized that he'll never have a chance even though Eren is gone now). I think the ending just kind of told us that Mikasa will always hold Eren in her heart and will never be able to let him go, which is why she wasn't with their friends and was just in her normal street clothes while sitting at the grave. It's like she just decided to live a quiet, peaceful life while loving only him and separating herself from everyone else (which is what makes the ending for Mikasa so said, because she'll probably never move on)

It would have broken many people. That's why he changed it. The series became too popular and would have let down too many fans. And while I'm normally in favors of leaving the writers alone and letting them do their own thing with their own work, I'm glad it didn't happen this time. Even this ending was pretty depressing.
We need a side story for mikasa happy ending
( T﹏T )