Fact: Elly's delusion that she's the only person on the planet not engaged in what Alan Moore calls 'donkey bonking' is an unwarranted and unnecessary complication that has the effect of prematurely destroying relationships that would have collapsed on their own less painfully.
Of course, keeping him from 'hurting himself' is not the only thing she's trying to protect him from. We also have to contend with the fact that just as Paul was made of snow and would melt, Rhetta was clearly The Wrong Sort because she would have kept Mike from pursuing the destiny Elly picked out for him. We sort of got a hint of this really meant when she wanted him to write about Farley's death. That would have been a terrible thing because it would have led to a terrible conclusion of hurting Elly and revealing her to be the same oblivious moron parent she was in 1979. Since Rhetta and Martha thought of Elly as being a person instead of a role model, let's just declare a tenth Foob Fact right here and now:
Fact: Her untoward prurience is a smoke-screen because she's really afraid that a love interest might get in the way of her owning Mike's horses.