Separation is a component of one of Illinois' no-fault divorce grounds: irreconcilable differences. Unlike in many states, this requires living apart from your spouse in Illinois. You must do so for two years, but you can waive this rule and shorten the time to six months if you and your spouse both sign an agreement. Prior to 1989, living separately meant just that – you and your spouse would have to live in two different households. Now, however, living separate lives in the same household can qualify under some circumstances. You and your spouse might have a right to continue living in the same home during Illinois' irreconcilable differences waiting period, but check with a local attorney to be sure.
Illinois is pretty firm in its position that issues of cohabitation should not affect property division in divorce. Even if your cohabitation is perceived as adultery, an Illinois judge is not permitted to consider this when dividing your assets and debts. One significant exception exists, however. If you spend marital money to support your relationship with someone other than your spouse, you can be held accountable. This is "dissipation" of marital assets – you spent or gave money away to a purpose that's unrelated to your marriage. If you file for divorce after January 1, 2013, your spouse must notify the court that he intends to pursue a claim for dissipation of marital assets, and the court sets a limit as to how far back before your separation these claims can apply. If the court finds that you dissipated money, the court will include it as part of the marital property you receive.
An Illinois judge can't withhold or award alimony as a punitive measure, to punish a spouse for marital misconduct. He can factor it in to whether you need financial support if you're seeking alimony, however, and he can weigh the fairness of requiring your ex to pay toward your new relationship. You have the right to live with someone else, but you might not have the right to financial assistance from your ex-spouse if the court determines that your relationship with your new roommate is happening on a "resident, continuing, conjugal basis." In other words, you're living with someone, you've been doing so for a while, and you behave as though you're a couple. Presumably, his income helps support your household. If you cohabit under these terms before your divorce is final, a judge can deny you alimony. If you do so after your divorce is final, your ex-spouse can petition the court to terminate your alimony award.
Effect on Custody
Illinois courts have held that a parent's behavior or actions have no impact on custody unless it affects her child or her relationship with her child. This is a somewhat nebulous rule, however, open to the interpretation of a judge or a custody evaluator. If you're living with someone else, particularly if you move in with him early on in the divorce proceedings, your spouse can make a claim that it's detrimental to your child. If you have plans to move in with someone, speak with an attorney first to find out how it might affect custody.