Emotion Immunity

Not to be confused with The Stone, the person who feels no emotions at all .

No matter what happens to him, Guy doesn't feel any emotions that'd slow him down. If Ava dies, he'll mourn her death, but only to end up continuing on his path a short while later. This could be because Guy is The Badass, The Edgy One, has a Hardened Heart, or just doesn't care about his friends' deaths anymore because of how common it is for them to die.

This also applies to if Guy is going through a horrible life but doesn't let it get in his way. This is if Guy is The Pitied in some children's media and the creators decided to not make Guy too realistic to the point where if the show wasn't aimed at kids, he might be suicidal.