What that phrase means, at least from my perspective, is that you can’t fill the holes in yourself with someone else. I don’t believe it means that you literally can have no authentic experience of love — either giving or receiving unless you have arrived at full self love because you’re right, that is a process. And you’re also right that someone else’s love and care can help you learn to give that more to yourself- but you still have to do the work and go on the journey to make the most of all of that. That’s what I think is the intention and meaning of that phrase.