For me, the only way to practise loving purely is to extend your love out from the people in your family to the people surrounding you, then to others. When you love, without expecting anything in return, that love is pure. When you love, unselfishly, that is pure. When you love others naturally, that is pure. When you love others, and take on everything so that they do not suffer, that is pure.
Sadly, pure love is going downhill, because nowadays, even parents love their kids with an alterior motive. Yes, it can be the best love in the world, but, mostly, it is also for other reasons.
If only loving others was so simple. There would be no war in the world.