She couldn't tell him. Right then, at that moment, Marian knew she couldn't tell him. It would turn his world upside down and hadn't that already been done enough here? Bringing him so far into the future to fight at the end of the world? Being confronted with Gisborne first thing and finding her safe but already acclimating to a new world without him? He was handling it all right, but telling him the truth... No. She wouldn't do that to him. Once he'd had time to settle, once he understood this world better, then she'd try and bring it up. And only hope he wouldn't do something rash and foolish that would stain his soul forever.
"My father," she chose instead, knowing her reaction meant he needed an answer of some sort. "He was killed. I actually came to live in the forest with you and the gang for a bit." He would enjoy that. It would give him at least an inkling as to why she was considerably more clingy than she might have been without telling him they'd said their marriage vows while being all but near death. Another blow she'd have to keep to herself for a while. "I ended up back in the castle, though, playing spy for you." And she wouldn't tell him about Allan, either.
She'd never kept this many lies from him and it was in danger of tearing her apart. But she'd rather cause herself harm than the man she loved so dearly.