If you mean "companionship" as in "romantic companionship", not even close. That's a very bold and inaccurate assumption to make.
The dictionary definition of loneliness, and the one that the board generally seems to go by, is:
"sadness because one has no friends or company"
It refers to feelings of general isolation and lack of contact with ANY human beings- not a lack of romantic partners or a desire for intimacy. Indeed, the overwhelming majority of people here not only have no desire for 3D intimacy, but also frown upon it.