As an introvert, I've spent most of my adult life by myself. I was raised in a big household with five older siblings, and I have a very close bond with my family. With the exception of a few close friends in and outside of the workplace, I have kept mostly to myself. I haven't sought out any romantic relationships in decades. I'm single and will likely remain that way for the rest of my life. Solitude has been my friend for a long time, and to be honest, it's not bad at all.
There is something else to solitude, and that is a sense of individuality. Our society is conditioned into thinking there's a "one size fits all" plan for everybody. While it's great if you can find the love of your life, raise a family, have a rewarding career and then retirement, it doesn't always work like that for others. And it's okay. You forge your own path. You don't have to conform.
"Loneliness is the absence of the other. Aloneness is the presence of oneself."
--Osho