Decline.

She gives you a disappointing look, "Ah, come on. Don't be that way."

"I'm sorry, I just don't know you enough."

The sheep-girl bursts out in laughter, "Human! You really are an odd character! Alright then, if we ever meet again."

As she turns to leave, you catch a glimpse of a hateful expression. She must not like you after denying her offer.
With the first sun already set beyond the horizon, and the other soon to follow, you think it best to return back to the camp you had found earlier to get some rest before starting up your search again in the morning.