Yes, some states still have fault grounds for divorce. At one time fault grounds were used to "punish" the guilty party, but even in those states that still have fault grounds, fault is no longer used as a reason for punishment.For example, if the husband was at fault, by being mentally cruel to his wife, a court would traditionally have made him pay a large amount of alimony, to punish him for his marital fault. If, on the other hand, the wife was at fault, by having an affair, then court would punish her by reducing her alimony payment or by giving her less marital property than she would have received otherwise.

Yes, either of you could use the fault of the other as grounds for a divorce. Interestingly enough, at one time fault by both parties sort of "cancelled out" the other. That is, if both the husband and the wife had affairs, neither of them could claim the fault of the other in order to get a divorce. They were stuck together in the marriage. As you might imagine, this result was less than satisfactory and makes very little sense. The grounds are typically set forth by the spouse who is filing for the divorce. It is up to the non-filing spouse to file a response to the petition or complaint either accepting or countering the stated grounds. It is common for spouses to not agree about the grounds of the divorce, but the non-filing spouse may choose not to argue over it, so the divorce process will take it course in a quicker fashion.