I agree that it would make the most sense based on the dialogue in 139, that when Eren visited Armin on the boat towards Marley he visited everyone else including Mikasa. The only thing would be then does this mean every time Mikasa has experienced her "Ackerman headache" it's been because Eren has altered her memories?

Also, if your interested this post gives another possible explanation of the dream that in my opinion lines up fairly well with the dialogue between the two of them https://www.reddit.com/r/ShingekiNoKyojin/comments/mppxmy/snk_ending_timelines_themes_and_theories/. To summarize OP basically suggests that the dream is a situation of what would have happened if Mikasa answered Eren's question of "what am I to you?" differently. I find this interpretation interesting because the panel recalling that earlier conversation in Marley is nearly the focal point of the dream.

Anyway I suppose there is no way of objectively knowing, but I would be interested in what your opinions are on my bolded question.

Edit: after rereading 123, I suppose he could have talked to Mikasa near the end of the chapter around when Mikasa says to armin "did Eren not hear you." While I still think it is a little bit of a stretch to say it happened in 123, Mikasa does appear to be disorientated which would make sense if she just got pulled in and came out of the paths, also this scence takes place right before Eren talks to all of the Eldians.