People get married for countless reasons besides the physical ones.
Well Liza and Judy were just following their unconscious attraction.
People seek their parent in their mate, and since both of their father's were gay, they were stuck looking for gay men.
For the "why" that happened, we'd probably have to find the first grandma back in ye olden days who decided the local fop was a good catch.
Because that's who asked them.
Straight guys have no interest in rich, famous, powerful women.
They make them feel inadequate.
Gay guys, however, live for that shit.
R6 Nailed the big reason. A lot of straight men ultimately have a problem with a woman who has more influence or money than them. Even in celebrity couples, you'll see the male having made more money than the female, or having more respectable credits.
Also, gay men tend to not take physical advantage of women, which even some of the nice straight guys can do sometimes.
A rich, powerful woman needs a richer, more powerful man to have any hope of keeping a marriage together.
Those kind of guys aren't looking to deal with the bullshit.
They can get someone younger and hotter who will idolize them without all the diva drama headaches.