You're right - even my relationship with my fiance is based on us wanting something from each other. We want to love and be loved - to care and be cared about. Are we "using" each other? Maybe, but there's no manipulation involved. We wouldn't want any part of it if the other wasn't enjoying the relationship.

I believe what's intended is that it's wrong to use people with disregard for their feelings and desires. We have a lot to gain by treating each other as willing partners (as with my fiance) rather than as tools.