How do we explain Mom's AD to Dad, who also has it?

Both Mom and Dad have AD - - different degrees, different manifestations. Mom's is "worse," because hers is manifesting with delusions/ hallucinations of jealousy; Dad's making it worse, 'cause he seemst to triggers it - - he doesn't "get it," not to be argumentative, etc. Even though they both love each other immensely. But when Mom gets into this mode, it's really hard to get her out of it. We try redirecting, etc. But the real frustration is that we know that ultimately, it'll pass. Dad, though lucid, and tho we've talked, and explained, and provided educational materials and counseling, just not does not "get it . . . ." He doesn't get it that he triggers it; he doesn't get it that he makes it worse . . . . . He does not seem to have any "problem-solving" skills left . . .. . It's so distressing to everyone.