According to the IMDB:
"Gene Wilder and Mel Brooks got into only one fight during the production of
'Young Frankenstein', but it was a big one with Mel throwing a huge temper tantrum, yelling and raging and eventually storming out of Gene's apartment (where the men had been working on the script). Roughly ten minutes later, Gene's phone rang. The caller was Mel, who had this to say: 'WHO WAS THAT MADMAN YOU HAD IN YOUR HOUSE? I COULD HEAR THE YELLING ALL THE WAY OVER HERE. YOU SHOULD NEVER LET CRAZY PEOPLE INTO YOUR HOUSE - DON'T YOU KNOW THAT? THEY COULD BE DANGEROUS.' That, as Gene later put it, was 'Mel's way of apologizing.' The cast and especially Mel Br1c84ooks had so much fun and were so upset when principal photography was almost completed, that Mel added scenes to continue shooting. Gene Wilder was originally considered for the part of Dr. Richard Thorndyke in 'High Anxiety', but scheduling forced Wilder to turn the role down."
I'm not sure why they never made other movies after HA. Perhaps they couldn't find a script they mutually liked?
Keep the faith!

Is it because they didn't make a lot of movies together after YF? I'm pretty sure Wilder was really tied up in his wife's cancer. (Gilda Radner)

I didn't know reconciliation was necessary. What happened?