[orthoganol]

Same age, everyone is different, but my experience is at least in your 20s when you're getting your first tastes of cohabitating relationships:

1) Starting cohabitating relationship: First a transition period where you lose sleep, but then you sleep like a baby, you don't stay up late thinking or worrying about x,y,z. The downside is you find yourself in a stagnating ball of comfort and end up challenging yourself a lot less because you're just too comfortable. (I look back at how lame I became in some of my cohabitating relationships, and could say the same for others I know, but would not to their face.)

b) Leaving cohabitating relationship: You sleep like a baby at first (nice surface feeling of independence), maybe for a couple months even, but then you grow anxious and feel negative effects of dependency withdrawal, and then end up losing a lot more sleep staying up late thinking or working. That can last a while, until you find another cohabitating relationship or find a deep rooted sense of independence again.

Again, likely different when you're older, but I think that's the general trajectory of being in cohabitating relationships in your younger years.