If they decide and then change their mind, it still counts as long as the decision lasts to the end of an episode.

I excluded the last episode to avoid flashforwards like "in the future they eventually divorce", I want this to be plot-relevant. If they renew Succession for the next season (probably won't), the decision in the last episode of the 4th counts.

Marriage annulment or stuff like that counts. Separation without divorce doesn't.

Mar 11, 8:30am: Will Shiv and Tom decide to divorce in the last season of Succession, but not the last episode? → Will Shiv and Tom decide to divorce in a following season of Succession, but not the last episode?

Mar 11, 8:30am: Will Shiv and Tom decide to divorce in a following season of Succession, but not the last episode? → Will Shiv and Tom decide to divorce in the 4th season of Succession, but not the last episode of the show?