KC.

“Sebastian Stan has above all become that familiar face for many fans of the Marvel Universe, that of a mutilated, frozen, ex-American soldier turned ruthless killer. It’s James “Bucky” Barnes I’m talking about, of course. Sebastian Stan has been donning the Winter Soldier’s costume for ten years now in the Captain America film series, the Avengers, and other TV series. But it’s above all, because he succeeds in conveying the pain, doubt, redemption, and above all, hope of this broken man caught up in the torments of his past.”

from what I know I think they needed a reason to not have Steve/Captain America v1 show up again cus of contract shit which sure, but there are much better IN CHARACTER ways to do that

first of all: Peggy is great and all but that whole plot line is at most a 'I dated her in highschool' level of relationship. he kissed like 1 time

second: he loves bucky way to much for that. just no. even if u somehow, trhough and enormous amount of homophobia and heteronormativity think that they aren't in love and don't at any point think about marrying eachother when they find out thats legal, their bond is far to strong to be sacrificed by steve for peggy. no.

third: remember all of age of ultron? that part where it's essentially implied that steve can't age? whered that go marvel??

fourth: same movie, different aspect: "God's righteous man. Pretending you could live without a war." -Ultron. He deserves to retire yes but 1) theres no way he actually would (this is the kid from brooklyn who fought when he could barely breathe) 2) he would want to be around just in case (remember half of the reason he took issue with the accords? "What if there is somewhere we need to go, and they don't let us?" -Steve) he would stay in his time just in case he's needed 3) he should retire with bucky, the only person whose been there for almost every part of his life, or at least somewhere where bucky is involved

so, my solution?

he comes back, gives the sheild to sam, finds a place to have a home where bucky would also live whenever he wasnt busy with his stuff, and ignores the outside world except for major updates (think he has a single phone with numbers to all the important people but otherwise he can just live his artist life inside his house and get updates from bucky on when he'll be home next)

the closest to in character that I think we would ever see of Steve "fighting bullies since I couldn't breathe right and running into war to save my best friend against orders twice" Rogers retiring and not showing up again

and this is only really an option cus I understand that actors cannot stay with one movie franchise for their whole career and everyone would notice if you switched out chris evans

Steve in CATWS,

Steve in CACW,

and Steve in AIW when he loses Bucky again.