The newlywed causes turmoil by suggesting to husband Paddy that they secretly take son Leo with them to New Zealand, despite Marlon's court order preventing it.
In an interview with What's on TV, Henry said that the difficult situation has led to her erratic behaviour.
She claimed: "Rhona and Paddy have become so set on their dream, they're not thinking straight. Any common sense has left the building so Rhona's a bit armed and dangerous at the moment."
She continued: "Paddy's job package - the house and fabulous salary which will allow Rhona to stay home with Leo - is now or never. That's why Rhona and Paddy are so extreme in the way they react."
When asked whether she thought Rhona and Paddy were somehow justified in their actions, the 38-year-old was adamant: "No! I'm a mother of two and thankfully very happily married. But I have many friends who have split up and I know how ugly it can get and I would hate to have that done to me.
"It's a truly tricky situation, but I don't think she's doing the right thing. I think she's being awful."
Co-star Mark Charnock, who plays Marlon, recently said that the Marlon/Paddy/Rhona feud plot-line had been one of his "best ever".