It seems like common sense that spousal support should end when the former spouse moves in with a significant other on a “conjugal” basis. Illinois law reflects this idea and specifically allows for termination of maintenance retroactive to the time of cohabitation. See Illinois Marriage and Dissolution of Marriage Act 750 ILCS 5/510(c).
The Courts have held that when a party receiving maintenance engages in a relationship with someone that mimics that of a husband and wife relationship, that person is deemed to be in a conjugal relationship. The problem is proving that a conjugal relationship exists. Some examples of a “conjugal” relationship include moving-in with a significant other, mixing of finances, and formal declarations to others (i.e. Facebook relationship status) that the parties are in a serious committed relationship together. In order to prove that there is a “conjugal” relationship, parties often have to employ the services of a private investigator in order to obtain evidence. Absent any concrete evidence that the parties lives are intertwined in such a way that mirrors a marriage, a judge will not likely terminate maintenance merely because the other party has a boyfriend/girlfriend.
Once a court determines that the recipient of maintenance has in fact been cohabitating with another, that Second and Third Districts have determined that the termination of maintenance is triggered upon the date of cohabitation and not the date of filing. In re Marriage of Gray, 314 Ill. App. 3d at 253, 247 Ill. Dec. 169, 731 N.E. 2d at 946 (Ill. App. 4th Dist.2000); In re Marriage of Snow, 322 Ill. App. 3d 953, 957, 750, N.E. 2d 1268, 1271 (Ill. App. 3th Dist., 2001). Fourth District cases seem to show that courts will only terminate upon the date of filing of said motion. In re Marriage of Stanley, 133 Ill. App. 3d 963 (Ill. App. 4th Dist. 1985).
If you suspect that your spouse who is presently receiving maintenance from you is engaged in a serious live-in relationship, you should talk to an attorney about what evidence you will need to obtain to make a case for cohabitation.