Modern forms of marriage are, in essence and overwhelmingly, a coping strategy to mitigate the uncomfortable feelings of being alone.
They are deal making. You keep me from feeling my alone feelings and I'll do the same for you. It is why the majority of such arrangements are wrought with suffering, conflict, and unstable times of peace. As much as we'd like to and as much sense as it might make, you cannot outsource this work to another human being and expect to have a good result, let alone the result you were looking for: to not feel alone.
The irreducible truth is this. You are alone and will always be alone. You entered this world by yourself and you will exit it by yourself. Though others might be around and have a particular or vested interest in you, they are having their own alone experience and you are having yours.
Nobody else is having the experience you are having and that is, in a way, lonely.
The Buddha is quoted as saying, "Life is suffering." What he meant was that life, inherently, has certain discomforts built into it—loneliness being chief among them, if not the primary one.
It is like an itch that can't be satisfied no matter how often or how hard you scratch it. While scratching does temporarily provide relief, as sure as the sun will rise, inevitably the itch returns again and again.
This presents quite a conundrum to logical, reasoning minds that think in terms of problem/solution. Surely, there will be those content with the pleasure-pain-pleasure cycle associated with treating loneliness through external measures, like marriage and others forms of partnership, including business.
Logistically speaking, it is far "easier" to rest here than venture further down the path. However, the suffering and drama remains and, over time, increases in magnitude, manageable though it seems.
Eventually, the frustration of seeking and not finding leads to alternative forms of inquiry and alternative solutions. If you are reading this, then you are probably in this category of people.
It begins with the liberating realisation that we are alone and that there is no external cure for it. (This does not mean we do not seek out marriage or company, it means we will not expect our loneliness to be treated through these things, which could very well entail not seeking them out.)
We then start to get curious about our nature and the alone feelings associated with it. Our attitude shifts from doing to being. We might pick up the practice of meditation and develop the ability to "sit" with our disquieting feelings without trying to change them. We might then start to understand there is no difference between pleasure and pain, or rather see them as two equal sides of the same coin.
That was the magic trick the Buddha was trying to point us all towards. Yes, life has suffering. But we are the cause of it, by wishing that it didn't.
This way, we become more like expansive vessels rather than rigid individuals with preferences, fighting for what we think we want and need.
You will always have your particular unique signature and idiosyncrasies. What you lose in your practice is your neediness, or the hunger we call loneliness.
When our needs evaporate through realisation, there is no further experience of being alone because there isn't an individual anymore, in the way you currently reckon it, to feel alone.
You are there. The full, whole you is there. All that changed was a hard won shift in perspective, like waking from a dream you were so sure was real.