Sometimes, enemies are programmed to read your inputs for maximum frustration. If you're both blocking, and you hit "X" to heal, they're "trained" to attack within the seconds of the healing animation. It trains the player to distance themselves before performing any actions that might make them vulnerable to enemies in close proximity or enemies with ranged attacks that can capitalize on "sloppy" play. Not saying it's fair or fun to learn, but, I've learned it.
The problem is that plenty of them are ALSO programmed to just fucking follow you, and they invariably move faster than you, have lunge attacks that cover half the continent, thus never actually giving you space to breath and heal.
You both are probably just going about it all wrong.