Do you think Jesse ever wakes up in the night, crying over what Lukas said--about all her failures, especially with Reuben--and all Lukas can do is sit there and hold her at a loss of what to say because he feels deep down that /he/ did this to her?
Honestly that’s exactly what I think. I headcanon that a lot of things that we see happen to Jesse haunt her at night and that moment has a big bunch of fun things she holds guilt for rolled into one, so it’s a very frequently recurring moment in her nightmares.
In his head, Lukas knows that was said was PAMA, but if he’d only been stronger, able to fight it, he wouldn’t have been used to hurt her so much. And every time the nightmare happens the guilty feelings gets worse because that horrible moment just keeps on hurting her because he couldn’t be strong enough.
And Jesse would just cling to him and cry, rambling about how she failed them, how she failed him and have no idea how much Lukas blames himself for it. If she did she’d probably suffer in silence, feeling guilty about that, too.