The most emotional scenes in the MCU aren't always the moments immediately following a character's end (although those always hit hard). Sometimes, the truly emotional scenes are the quiet ones where a character finally reveals their true selves to the audience - the scenes in which a prickly or defensive superhero finally lets their guard down, and the audience truly wishes they could step through the screen and offer them some small sense of comfort.
The MCU is filled to the brim with tragic moments and heroes - characters who put their lives on the line so others can have another chance at life. Most of the time, the Avengers and other MCU heavyweights are great at putting up a front of bravado and humor. However, there are certain scenes throughout the franchise where the bravado cracks just enough to see the broken hearts hiding inside them.