The weight is on his back.
Luke has to be a leader. If he can't, he'll be killed. He's too far into this to turn back. He does everything Kronos orders him to do, but he can't keep undergoing the pressure anymore.
Not when he's still seeing you.
Luke is very aware that he's putting you in danger when he sneaks out of the Princess Andromeda to see you, but he really can't help himself. Luke has to have some way to not go insane.
You're the only thing that keeps him calm.
Unless there is a dagger to your throat. Then, he is not calm when it revolves around you.
"Drop it." He commanded one of his soldiers. "What? Luke, she was down in the boiler room, setting up bombs!" Luke looked slightly betrayed. He had told you nit to get involved, but he recovered. "Put it down." He demanded angrily.