I...don't actually get why he's lying to her about having found some random ancient book and whatnot. He's already said he's in love with her and has a very high chance of staying with her forever, just man up and say you uncontrollably get insights into things at times, then don't tell anyone else. At this rate he's going to have to invent random manuals and journals for blacksmithing, formations, and general cultivating that mysteriously all vanished after he read them...which sounds very trustworthy.
arten_d