Dudebros:"Go ReAd ThE cOmIcS".
The comics:
Steve telling Bucky he felt helpless when he thought he had lost him and that he'd prefer a punch from Hulk-

- Steve thinking of Bucky and of their time together at every chance-

- Steve losing his mind whenever Bucky was in danger (and we can count on Zemo knowing that the quickest way to break Steve is by torturing Bucky, in the 3rd picture Steve is yelling at Zemo)-

- And of course Steve having the chance to live a dreamy life with Sharon but giving it up at the possibility that Bucky could die in that future.
"What I saw when they were pulling me back through time. It was like split seconds of my future. Or was it my possible futures?-

- More than one?"-

- "Are they both true? Can they be? Or is it some kind of warning?"
This is from:"Captain America: Who will wield the shield?" by Brubacker, Guice and Ross.
Steve would do everything for Bucky, I'm not even talking about the ship, Bucky means the world to him.