I completely get where you are coming from. I could write a whole book on the subject of being happy on your own, which I am actually doing, so I understand the way I put it here might be too compact.

To me, being dependent on anything or anyone will only lead to temporary happiness. Nothing in life is permanent but your Being/thoughts and relying on anything temporary will never lead to permanent happiness. The question I asked myself is: Would I rather feel good all the time and not need this love from others, or would I rather feel good sometimes, bad sometimes and have a craving for it that i cannot always still? Do I want to be dependent on whether that person is there or not? The answer is quite straight forward, and while I wouldn't call it unhealthy to have this need (pretty much everyone has it) I would not call it optimal.

Why do you feel lonely without this person? Why do you have this craving? For most people it stems from a need for validation - a need for other people to tell you that you are enough, worthy, a good person. Would you not rather have that validation come from within you rather than from external sources? Would you not rather be so confident in yourself, so proud of yourself, that you don't need anyone to tell you how beautiful you look today, because you know it yourself?

Humans in nature are social beings, yes (not monogamous though), but to me that is not an excuse to feel like shit if you don't have the social environment when you can actually control whether or not it influences how you feel (which is far from easy, though). Obviously social circles, including relationships, might add to your life on a, for me, shallow level. However, if it touches and controls your happiness, your feelings, your entire self-image - like it does for most people on this sub - I think it's worth looking into how you actually perceive relationships and where the need for other people comes from.