Amy gave him an opportunity for some "fun" time at the end of the 4.7 update. However, uncharacteristically, Frank, somehow declined Amy's sexual advances despite his willingness and eager to fuck her in prior events. The developers made Frank a completely different person by the end of 4.7, of course, it's to drag on the story and milk Patrons. But the way they blue balled everyone in 4.7, it just does not make sense, as we have come to learn it would be so uncharacteristic of Frank to turn down the chance to get in Amy's shorts.
You know it's bad-story/character-writing when the creators made the horniest character to suddenly want nothing to do with Amy (this is all just IMO; developers, don't get offended).