There's a false representation here.
A person cannot make us happy, nor does a family, and to say a family can be 'truly happy' whatever that means is ridiculous.
We have to go with the empirical evidence here, overwhelmingly the evidence that loneliness is literally a killer.
single people living alone are mire likely to commit suicide and ironically as a society we've engineered a state of affiars in which singledom is growing. That's partly because the idea of the family has fallen into disrepute, at least to some extent, and because we have a different notion of what constitutes happiness-one that requires self fulfilment rather than the discharge of duties within the family.
So we put ourselves at the centre of things-we measure our happiness and relationships are found wanting, well of course, that's because a person cannot make another happy. We gain happiness because we are with another, that we transcend our own state and have to be realistic about that situation.
Humans are socially defined beings, the idea of 'i' comes linguistically fro our relationships to the group, we only exist in a quite fundamental in how we relate to each other.
Being in a relationship gives us a basis on which to relate to the other in a different way, it helps us to become subsumed into the other, and while all relationships are imperfect, our problems come not from the imperfections but with our inability to accept the imperfections of others.
Gotta admit, there were a few lines in your post that struck a chord in me:
"I haven't come across one family who look truly happy. Happiness doesn't come from a relationship. It comes from within."
Nevertheless, speaking from the perspective born of compulsive loneliness, I wish you joy and good companionship.