It's called being Flanked, which is pretty much exactly what you're talking about and you get -10 Deflection from it.
Engagement is one of the reasons why using melee characters in situations like this is pointless because if you make a single pixel move, you get hit by a 90 damage attack with no animation, even if the bear is currently recovering from a swing it just made. Without Engagement you can actually use cool tactics like rotating aggro off the bear.
I need to make a video demonstrating that tbh but I gotta wait for Bester to convert the IE mod to v480.