why did RED say thart"when the time comes, I'm not by on your side".

I accidentally disliked, but I meant to like

Not sure what she means by that. But basically she's in love with Ruce and this is the second time Ruce has abandoned her without warning. She wants to stay with Ruce and help her with her issues. Meanwhile Ruce doesn't believe she can without putting herself in a lot of danger. The fact that Red knows Ruce is a special beast man literally means she should be dead right now. And if Ruce wasn't in love with her and actually following her duty she should have killed Red. Even though Red's life is being spared by rules/duties not being executed... she still wants to dive head first into Ruce's world and her problems. Since Ruce knows this and is traumatised from that incident where Red was about to be killed by that bird basket case loony toon and Ruce was like almost completely useless. She's scared the psycho bird will actually succeed in killing Red if she doesn't take her out of that war environment. But yeah even though her motives are in the right place and she only wants to protect Red. Red doesn't see it that way. She probably may not even understand what or why Ruce leaves her. She may also not even care about the reason and just hate that she can't trust Ruce and hate that Ruce never let's her in and allows her to share the burden together.