Heartwarming: Street Fighter II: The Animated Movie
Guile and Chun-Li. Note how Guile never mentions he has a wife? That's so that it doesn't seem so weird when he's showing all that affection for Chun-Li - especially when she's hurt by Vega and fighting for her life. He stands by her bed and promises her he's going to get revenge while she's comatose/unconscious. Then at the end he sheds Manly Tears when he thinks she's died.
It's even more heartwarming when you consider that Guile and Chun-li's voice actors as of Street Fighter IV are now married. Could this be Heartwarming in Hindsight?
Young Ken ripping his red gi to bandage young Ryu's bleeding forehead, since in this continuity that's how Ryu got his famous red headband.
When forced to face Ken, Ryu absolutely refused to fight him, recognizing that Ken wasn't himself. Instead, Ryu kept trying to get through to him by reminding him that he was his friend, interwoven with brief flashes of their training days, which showed that his words were reaching him. Ryu takes a beating, but ultimately succeeds without throwing a single punch. Ken was moved to tears.