Okay, let's start with guilt for abandoning her not just once, but twice, after the Other Guy caused a mess out of everything? Throw in guilt over getting her pulled into this mess to begin with.
Add in the fact that I hadn't tried to contact her after I became an Avenger, how I wanted her to be able to move on, how I didn't want to know how she did even though I stalked her on social media.
Finish it off with how I'm not fifteen years older than her, my hair is all grey, I've got wrinkles all over, and I look like an old man.