Castle season 8 has had some pretty terrible twists (the convoluted LokSat conspiracy, too many new characters, weird sitcom style humor) but the worst of them was Kate walking out on Rick. With nothing more than a vague explanation, Beckett moved out of the loft in order to “protect” Castle.
The separation not only made no sense story wise (would the bad guys really not go after her husband simply because she'd moved out?), it was a slap in the face to viewers who had waited years to see Caskett as a happily married couple. Now fans are screaming for a return to what made them fall in love with this show in the first place: the romance of Castle and Beckett as a couple solving quirky crimes TOGETHER!