It is an interesting question. I myself have not experienced loneliness for 15 years. I always imagined this "siddhi" (to not feel lonely) to be a linear attainment: one obtained by anyone at this stage of development. But, now you are making me reconsider this. I always considered you more advanced than me in meditation. But, there are many mysteries to this quest I am always learning. Perhaps it is not a linear process.
I did follow a very ascetical path in my own journey. I have not had a long-term partner. I viewed this privation as a part of my training. Something given to me as a challenge by the divine. I saw it as a means of giving me something to struggle with, so I could be awarded a "spiritual crown" through long suffering and patient endurance. It was a hard path; but the friction of it I do believe caused an alchemical change... I do not experience loneliness or despair. I have become a different kind of animal. (If I were to speculate on what this means I would suspect it has something to do with my I-hood transitioning away from the material self and building and strengthening a base in the immaterial self that is not affected by the world of matter.)
Another perspective on this... If we are all One, how can I ever be alone? It does not make sense. If we are all part of a divine Unity, how can I ever be separate? Is it not an illusion that I feel privation, loneliness, poverty? Are we not always One? Are we not always United?
Another idea. Am I not here on a temporary departure? Are my peers not the great ascetics, yogis, philosophers, and saints? Can I not count Socrates, Christ, Buddha, Juan de la Cruz, Teresa of Avila, Walt Whitman, and Patanjali among my friends? What better friends are there than these? Will I not be reunited with them, with the gods and noble ones, on my exit from this human life? What a great company of spiritual friends we can count on.