I had the same problem several times and also thought about separating. On one hand it is true that it is easier to monitor separated rabbits, but I always decided against it because stress is an aggravating factor in GI stasis and that changing my rabbit’s living conditions and taking away the comfort of having her husbunny with her seemed detrimental to her health. To check if she is eating, staying quietly in the room a few minutes to see if she seems to eat everytime you give something to eat is a good indication (a rabbit who doesn’t come running in the span of 10 minutes for her pellets / vegetables and who won’t eat immediately when you put food she likes in front of her is not well). For pooping, I just put my rabbit in her cage after cleaning the litterbox for about 10 minutes (at a time when rabbits are normally active, like around 6 pm) when I didn’t know exactly if she was eliminating normally. A rabbit who poops normally will leave at least 2-3 poops behind him in 10-15mn in his hours of activity.
If there is no poops (or that they are tiny, or worse, surrounded by mucus) and that she doesn’t show any eagerness to eat, I would say it’s time to see a vet. In the early stages of stasis, if there is no blockage, a dose of metacam and a day or two of reglan are sometimes enough to “restart” the guts. But the longer you wait, the more complicated it is to recover – not treated, some rabbits die from a stasis that could have been easily cured…