Don't worry about saying things like that out loud. Instead, make it a habit.
Tsubasa looks like a lot of characters named Tsubasa to me. Very androgynous. Despite the obvious boobs. It's probably the haircut.
Yeah, those are some warning flags.
If you can tell from a glance like that, they would know the cause. It's probably more subtle than that.
Yeah betting on the new girl to be the problem, it’s either she has a thing for the owner and is bullying any female who is friendly w him, or she’s just a bitch with any coworker.
If that's the case a girl starting to work with her boyfriend should be one of the safer girls to work with for a jealous character like that. Though we've seen the depths some girls in this manga goes to, so that's not a safe bet.