I know you said this, but I want to emphasize that relationship failures do not invalidate the value of that ideal. I struggle to think of anyone who wouldn't benefit from pursuing some kind of family, and I believe sacrificing that pursuit entirely is always a tragic mistake.
Forming loving families is hard. You might not find the right people immediately, and some people are incredibly destructive towards each other. Everyone is not compatible with everyone else. And it is often less painful to live alone than to live with a destructive family.
That means some families need to be dissolved and reconstituted, others need time to heal. For some people there is not enough time, understanding or strength to grow and form new bonds with others.
That does not mean people should give up and live alone. Anyone who believes they will be happier alone is deluding themselves and/or too scared of the pain of rejection and heartbreak. It's worth it.