What's important about being able to self-validate? As human beings, we cannot always depend on our significant other to treat us just the way we like to be treated. We are human, and each of us has our own perspectives and needs. That's reality. Because our learning is likely to love ourselves, we actually may have attracted someone who is not able to validate our inner child in the ways that we would ideally want.
What I notice is that when we place our attention on our partners for validation, we are away from our center. We are disconnected to ourselves and can feel uncomfortable....reactive...ungrounded. Is he/she validating me...or not? Am I okay in my partner's eyes...or not? From this place, it's very difficult to listen to and be with where our partner is at and then respond in a loving way with their best interest in mind.
For example, one of my clients is with a person who has difficulty speaking up for what he wants. When he risked asking, he said something that she didn't like and to which she could have reacted to in an angry, defensive way. Her challenge was to put his growing edge first by honestly being able to say that, even though she didn't like what he said, she appreciated that he took a stand for himself and wanted to encourage him to continue to do that. She let him know that she understood it was a big risk for him and took courage.
I acknowledged her inner confidence because she had to be solid in believing that she was okay so that she didn't get hooked by his comments and could be there for him in such an empowering way. Safety and trust were created for his inner child as well as her own because she stood her ground in feeling okay about herself in the midst of some chaos in her significant relationship.