Laertes knows that Claudius and Gertrude have a past together that he will never be a part of, half their childhood and all of their adult lives, and though they have loved each other always they could not be in love until very recently. Once again he starts to feel like he’s intruding on something private and personal, and once again two pairs of hands press him back down to the mattress – “which let me remind you, dear, we invited you to share” – before he can run away from happiness. It is a personal moment, but it includes him, and they want to keep him here for many moments to come.