Are realationships practical?

After watching the machine girl trailer me and my frind had an arguement over a 2 or 1 armed girl. My aregument was that she would appreciate you more for over looking her physical handicap and feel more of a sensual bond where as he says he would rather have a 2 armed girl for work and raising a family. Although the argument was merely personal perspective, do people often look for relation ships as a way to carries life's burdens of work rather than love?