He doesn't want his wife to eclipse him (or even come close).
Bill would like the mention of Hillary in history to be a small footnote by his name.
I do agree that they probably hate each other, on some level, but have too much dirt on one another to ever consider divorcing - in that sense they each have a gun to each other's head.
On the other hand, consider LBJ and JFK. No doubt they hated each other as much or more than the contempoary clintons. Yet there is at least a strong suggestion, if not outright evidence that LBJ blackmailed JFK to make him the VP candidate when JFK was all set to pick Symington, I think it was.
Now first husband is not the *same* as being VP, but in some sense it's roughly comparable - your as close to the throne as you can get without being actually on it - I would think that that would be a pretty strong inducement.
What do you think, Mia?