Me, trying to be rational:
MacCready was 10 in Fallout 3. I can't reasonably hold his actions against him in 4. If someone held me to what I did and said when I was 10, everyone would hate me. He's grown up, and an entirely different person now. The Sole Survivor wouldn't even have any idea of what he was like back then.
Me, internally:
I still remember Little Lamplight, you shitter. I remember your nasally little voice, you looking down on me while you squatted in your shitty cave eating goddamn cave fungus with your bullshit Peter Pan mentality. You expect me to romance you when you pulled that shit? I'll give you a swirlie you nerd. Who's the mungo now.
