You could call it an opinion. It's more of a fact though. Confidence is far sexier-- coyness is sexier-- a need for one's self identity in hopes of finding their purpose. These are the things which will lead to the relationship you're speaking of. The problem with most people is they're desperate for others to define them. They sacrifice their state of mind and body to find fulfillment. I call them relationship whores. They're hurting themselves whilst jumping from relation to relation.
I don’t think you understand the quote- it’s not necessarily relationship based! To me it’s wanting in the physical sense, and if someone wants you desperately and you want them desperately too, that is hella sexy. Sexier than them being confident.