Dear Smash . . . .
Cheating is not, in any way, sexy. It's not hot or awesome or anything else you're trying to make it be. And every main couple except for one is affected by it, it's running rampant in your show and I'm not amused.
I know that the rest of the season is already filmed and there are only a couple of episodes left, but I hope you don't continue to use this "theme" as a major part of next season.
And while I have your (metaphorical) ear, can we talk about Marilyn? I like Katherine McPhee, don't get me wrong, but Megan Hilty (and by extension her character) make a better Marilyn - she sounds more like her and she certainly looks like her. Also Karen (McPhee's character) is sort of hard to root for. And what happened to that producer that she was talking to before.
And please, please, do not mess with Nick and Eileen. They're awesome together. Leave. Them. Alone.
Also, Ellis is a terrible character, there isn't anything likable about him. He's a rat. I'm not saying get rid of him, but I don't see the point of him either. You should, my dear Smash, explain his purpose sooner rather then later.
That's all for now.
storywriter84