You are referring to the impact your cohabitation may have on the spousal support you receive.
Unless the parties have "otherwise agreed" in writing, the supported party's cohabitation with a person of the opposite sex gives rise to a rebuttable presumption, affecting the burden of proof, of decreased need for spousal support.
The supporting party seeking a spousal support reduction or termination need simply show that you are now "cohabiting with a person of the opposite sex." However, the statute contemplates more than a simple roommate or "boarding arrangement." There must be a showing of a sexual, romantic or at least a "homemaker-companion" relationship.
Other than giving you the above information, I cannot definitively tell you what impact, if any, your cohabitation may have on your spousal support payments. Unfortunately, my crystal ball broke a few years back.
The response given is not intended to create, nor does it create an ongoing duty to respond to questions. The response does not form an attorney-client relationship, nor is it intended to be anything other than the educated opinion of the author. It should not be relied upon as legal advice. The response given is based upon the limited facts provided by the person asking the question. To the extent additional or different facts exist, the response might possibly change.
By moving in with your partner, you do create a change of circumstances that can lead to a modification of your spousal support. As archaic as it may sound, the purpose of spousal support is provide you support to live at the marital standard of living. Even if your boyfriend makes less than you, you're still dividing some expenses (although probably unequally) and therefore partially being "supported" by him.
That being said, it is your ex-husband's job to file a motion for modification of spousal support, and you ARE entitled to a trial on the issue. As the previous poster mentioned, there is a rebuttable presumption, which means there isn't an automatic termination of support (unlike marriage).
You'll want to consult with an attorney before making this big decision.