MairISaoirse,
Great question and I'm looking forward to read what others contribute. Glad to hear that you are reading the 5 Love Languages and working on yourself.
From what I understand, validation is acknowledging someone; their thoughts, their feelings, etc. It does not mean that you agree with them. It's like trying to show empathy and attempting to put yourself into their shoes. For example:
"I hear you saying that you had a bad day."
"I can understand why you feel that way."
"I'm sorry that disappointed you."
Affirmation is communicating truths, or even your feelings to the other person. They are statements that help build up the other person. For example:
"You look great today!
"Your personality is one of my favorite things about you."
"You worked really hard on that project."
I believe that a healthy relationship needs both. I have read about many WS's say that they needed external validation. They wanted to be noticed, acknowledge. But I think they were also looking for affirmation. They wanted to be told that they were pretty, smart, etc.
And some people have shared that it wasn't enough to get the validation and affirmation from their spouse. Like, that was their spouse's job so it somehow didn't mean as much. It didn't matter if I validated and gave affirmation to my ex. I could tell her, "I'm sorry your parents put you down about your weight. But, I love you and I love your body." However, those statements somehow did not mean as much as when the OM probably told her the exact same words.
There is nothing wrong with wanting affirmation and validation. In fact, I think we all want that. But, who do we want it from (SO, parents, coworkers, etc)? That's where boundaries come into play. But, we also need to be giving affirmation and validation to others. Especially our SO, spouse, and even children.