Imagine:

You had known Steve for as long as he'd been unfrozen, befriending the soldier over the many years you had spent working alongside him during missions.

However, the blood on your hands was far too great, at least in your eyes. You were weak and broken, and Steve took notice to it. He strived to bring out the best in you, and make you see happiness again.

Yet, his attempts were in vain after he learned that you had faded away in the aftermath of Thanos, appearing at the scene of your disappearance, a car crash. (Gif above)

Suddenly, the Rogers boy from Brooklyn had even more of a reason to fight for redemption.