The other spouse, if they are not dating, may develop the idea that the dating spouse was committing adultery even if that idea hadn't surfaced before.Or, the other spouse may simply suffer anger and hurt as a result of the limited amount of time it apparently took the dating spouse to recover and move on.Marital misconduct can encompass a wide variety of actions, including adultery and cruelty.
Additionally, while every state is now a no-fault divorce state, marital misconduct can still be considered in some situations.
Either way, the other spouse may become confrontational, may become unwilling to compromise and obstinate during the proceedings, or, at best, may become cold and distrustful of the dating spouse.
In addition, in some states the new relationship may be considered in the division of property or alimony determinations, so the dating spouse may not get as much as they want out of the divorce depending on the new partner's financial circumstances.
This is especially true if the dating spouse begins cohabitating with their new partner during the divorce process.
For example, the judge might disapprove of the dating spouse's behavior and develop a bias against them.
While such a bias is ostensibly unacceptable in the U. legal system, judges are human and biases are natural and even probable in some instances.