To me that's one of the things I rather liked about Miribecca. Yes, when Rebecca first fell for a girl there was some fretting, but really, for soap standards it was kept to a total minimum (though chances are that this might also be why the storyline didn't last long, a soap will always favor the option with more drama).
I like to think that a lot of it is just Marlene's personality. She's a drama queen about a lot of things so it makes sense that she would be one about something like this too.
There's actually one thing that VL loves to do, where the person is completely scared of coming out and how everybody will react and then everybody around them is like "Yeah, whatever". They did that with Rebecca too where she told her dad and he didn't even bat an eye (though one could argue that might also have been a bit of "ah, those silly young girls and their experimentation phase").
I could very easily see that happening with Marlene, where everybody in her family takes it much more calmly. Though I have to admit, I'd love to see the face of her ex-husband.
They also like to pull the whole "I'm not mad that you're gay, I'm just hurt you lied/felt you couldn't tell me".
I have to say, if Marbecca ever get their act together, I think one really interesting thing to touch on would be that Marlene is also a singer who is supposed to be somewhat of a celebrity/public persona. One who has been in the tabloids a lot with her messy divorce and the rape. I could see why she would be hesitant to come out, fearing that she could lose fans or have people not take her seriously. I think they could do a spiel on the whole "out with friends and family, but closeted in public" thing that you had a lot of with real life celebrities (of course ending with a beautiful and awesome coming out).