Legal Question in Civil Litigation in Louisiana

No. It means someone to whom you are married. You specifically cannot have a girlfriend over, regardless of how serious your relationship is. That is what that rule is there to prohibit.

Affinity for someone means, technically, a special liking for them, however, in the Judgment you are speaking about, affinity means marriage. I agree with Mr. Lambert that you CANNOT have a girlfriend there overnight, and that includes a "fiance'." I do believe however, that your sibling's spouse can spend the night unless your ex can prove the 2 of you are sleeping together. In my opinion, one is related by affinity to one's brother's wife and one's sister's husband.

Affinity includes in-laws, step-parents, step-children and (if one must be hyper-technical) relatives by adoption.

I think all three answers specifically exclude sex partners outside of marriage. In fact, that is exactly who the rule is meant to exclude.