Number one: There is nothing someone else has that is going to "complete" you. If you are not complete and whole, you can never be a true partner to someone else. You cannot look to someone else to fill that hole inside of you, because then all you are is a suck. You aren't a partner, you are a leech.

One step further back: how does one become a 'whole' person, as well as illustrating such. I'd like to propose the idea that no single person really reaches enlightenment (sorry, definitely exaggerating, but not in a sarcastic sense). In other words, being 'incomplete' is the norm. Through engaging with a partner, each individual unlocks the ability to build upon themselves with a partner in good faith to reach a more wholesome state. This is based on the idea of one's attraction to another has a strong, positive correlation with values and upbringing - for better and worse. That said, through the 'worse,' one side can look to another for healing through compassion, comfort, and connection. Values aren't instilled in a void, they form through one's upbringing. Naturally, an upbringing calls for role models/guardians/parents. Through the rough times, your romantic interest has the power to enroll as the emotional and personal sounding board who can facilitate healing of wounds in the past as a partner in good faith. Inches by inches, wound by wound, progress can move forward towards a better being.

Wait. I rambled somewhere in that second thought process. I guess my point was, I agree here:

Everything anyone needs (short of an actually clinically-assessed chemical or mental imbalance) is inside of them already.

And those willing to take that healing a step further could be lucky enough to explore a better way to live and grow exponentially with others.

What I'm sorta reading is a scenario where people seek out others to complete themselves. I agree that's not healthy for any relationship. I'd further argue that the other participant in this diad likely isn't 'wholesome' either. It's not unreasonable to presume that those who are not 'whole' or 'comfortable' with themselves may find that in those they seek romantic interest's with are seeking the same on some level.

I think I mixed around a lot of sentences when trying to make this more fluid. I'd be more than happy to clarify if something didn't make sense.