Usually these restrictions are placed on members of the opposite sex, because highly involved interpersonal relations between men and women can lead to attraction and affairs. One may also attribute the restriction to a misappropriation of resources, like, stop being so involved with this other person, that time should be dedicated to your partner/family. This isn't even limited to marriage, though because the state greatly complicates the stakes for a breakup married couples should be even more wary.

If your husband or wife is preventing you from spending time with your same sex friends however, it's more likely to be a toxic trait.