So far on the show we've had the following breakups:
1) (prior to the pilot) Toby and his wife
2) Jim and Katy (the "Hot Girl")
3) Jan and Mr. Gould
4) Pam and Roy (round 1)
5) Michael and Carol
6) Pam and Roy (round 2 - sorta)

Am I missing any other breakups?

So what I wanted to ask is, who is next to breakup? Any guesses and/or reasons for your guesses?

Here's the list of potential breakup partners:
1) Michael and Jan
2) Dwight and Angela
3) Ryan and Kelly
4) Jim and Karen
5) Phyllis and Bob Vance
6) Oscar and his partner
7) Stanley and his wife (seen in the Dundees)

(I've limited the list to only characters that we've seen)