A Literal Fool
When the Fool card comes up in a reading is there ever a point where you might take the card literally, as in interpreting it to mean the person feels like a fool? ...Could that be read as him feeling like a fool for getting involved with her
Humanity has always needed that one person who does foolish things to make us laugh--which is why there have always been fools at royal courts, and clueless characters in plays. And yes, we in civilized times know it's cruel to laugh or mock people who aren't trying to make us laugh; who are just making honest mistakes. But we still play pranks and laugh at those who fall for them--and they laugh at falling for them too. We still watch comedies where people make dumb mistakes and, in scrambling to fix them, escalate their folly. We still love comedians who entertain us with monologues of their foolish moves. And, yes, sometimes that laughter is because the person looked at the thing very wrongly in their ignorance, in a way we never expected, in a way that might delight us as well as make us laugh (fish-out-of-water stories are all about such folly).
Ultimately, however, we're not laughing at them, but because these Fools help us to see, know, and laugh at ourselves. At the stupid things we've done. And in that laughter, we forgive ourselves for those times when we've been a Fool.
THAT is why the Fool is a major arcana. Yes, he can sometimes be an innovator that others see as foolish ("Men weren't meant to fly! What is that fool doing trying to create wings?") And there are those who are wise beyond their time that others mock because they're the fools and they don't understand. BUT, the Fool isn't just a major, an archetype for them. He is also a major, and archetype for our actual folly. Our actual dumb mistakes. The ones we make and post on YouTube for everyone to laugh at...and for us to laugh at as well, remembering, forgiving, learning from, and understanding that being silly, being clownish, being stupid, being unwise, is quintessentially human.
Answer to your question: YES. The Fool can stand for literally being a Fool. And I agree, given how you've described this girl, that this person got that card likely because she hasn't changed at all. What's changed is his perspective. The cards might be saying: "She hasn't changed, you Fool! She was always like this. You were too foolishly blind to see it."