Your life is for you and you need to have a perception to enjoy it to make it fulfilling and complete. Having a life partner is a choice that you make. Your partner shares the ups and downs of your life and vice versa when you walk through your journey together.
Completeness of a life depends on how meaningfully you can live it. And you and only you have the power to live it completely. Having a partner might add to the difficulties or ease the difficulties depending on the person you got. So he /she can be like a seasoning but the actual recipe always lies with us.
I just like to mention "Life partner is a part of your life but not your life in entirety".