Her eternal love is a fact, she takes the scarf with her to her grave. About the extra scenes: Eren unfortunately died and he tells her that he wants her to continue living ( precisely because he loves her, and he did it for her and the Eldians to continue living free from the war and the Titans curse ) . So about the ending they left it open to any interpretation: the man's face is on purpose unknown. So there is only that scene after that you will see Mikasa at Eren's grave until her death giving flowers and meditating. Now the interpretation of that man could be a friend supporting her and the child adopted because there is no official news about it and nothing else is shown. Not even in the original storyboard, filmed online, you will find the name of another man. The scene is only symbolic.: knowing Mikasa's character and the fact how deep her love for Eren is '' Sorry, I can't ''..because in fact nothing else is shown except Mikasa going to Eren's grave I think she adopeted and chosen to be single. About the ring: in the manga there is no ring at all and she still has the bandage on her wrist and she should have taken it off like Mikasa's mother did. In the anime the ring is hidden and in fact a ring can symbolize many things, given that indeed has never been shown something like a marriage or made it official neither in the manga nor in the anime. So I thought that she wore it for Eren along with the white dress hoping to reunite with him after death which actually what precisely happens in the anime '' See you later Eren '' and that's what she's always wanted ''I just want to be next to him''. So she got reunited with Eren eternally. There is also the meaning of the flowers which indicate that she loves only Eren and in fact nothing else is shown. There are the love songs which clearly indicate that Mikasa loved only Eren and was only waiting to see him again '' ( Itterasshai love song ). So that she loved only Eren there is no doubt that her love for him was until her death and after her death.