Just be honest

"So um... Don't freak out but I kinda...Lost... Yang?" She said bashfully.

Jaune immediately stopped Raven, looking at Ruby blankly

"I'm sorry. You did WHAT?" He asked

"It's not my fault! Sh-she just wandered off! Blake and Weiss are old looking for her but--"

Jaune stood up, putting his clothes back on and looking at Raven, then putting her back inton a trance.

"Raven. Go search for your daughter. If you find her, call me." He commanded. Raven mindlessly approached the window and opened it, leaping out of it to go search.

"Ruby... Come on. We're searching too" he stated as he began marching off.