Exactly. Ron pushed Patrick/Sabrina HARD. And he pushed Sabrina on the back of "dead Robin", even more so than Patrick EVER was, IMO. Sabrina used the Nurse's Ball in the name of Robin to ingratiate herself to Robin's widower. And in the process, Patrick's personality vanished to play Sabrina's prince. Ron even tried to make the Scrubs and Patrick/Sabrina pairings on equal ground with a kid and Patrick being torn. The only problem is? The audience called bullshit. And whether JT agreed or not, as @jsbt rightfully points out, he still played it.
And played the pairing once more when Patrick suddenly forgot his animosity towards Jason so he and Sam could play "happy family fuck adventure buddies."
Frank got rid of the writers that built Scrubs and replaced them with writers that couldn't do jack shit but "insta-luv". It's no wonder the pairings failed. JT saw the (bad) writing on the wall, knew Patrick meant zip to Frank as his own character, and he left. Seems pretty straightforward to me.
And the Gina Tognoni as Robin rumor sounds like a huge joke. And, anyway, I thought I read more than once that GT often traveled from back east to tape for Y&R, so unless she gets one hell of an offer, I don't see how commuting again to another west-coast soap would be of benefit to her (except that west coast soaps are all that are left. But I did read she commuted from back east. Maybe she will try for guest prime time roles?).