Ahaha right? It's like when someone approaches you at the grocery store acting like you've been besties for years, and you can't even recall their name. "Heeeey ...... you! How've you been >.>"
Irvine is legit one of the most interesting of the canon cast because he does remember; he has to carry that weight for everyone for such a huge portion of the game. And I always kind of saw Zell and Irvine as Squall's shoulder angles. Here's Zell encouraging him in wholesome ways (make a replica ring and match! It'll be cute!) while Irvine is all, let's set you up on a date and leave out porno mags for inspiration! In closing, this is their relationship:
OH MAN. YES. Paranoia all the way. It can reach sitcom proportions of misunderstanding that culminates in Elena tying Irvine to a chair and interrogating him. Spoiler: he just thinks she's a little kinky that way.