I don't like putting my players in blue-on-blue situations much. If one of them is playing an awesome-cool Ranger who likes to deal death with his longbow it's a buzzkill for him if he puts arrows into the party's Barbarian and Paladin as often as an enemy. I don't run annoying 'fumbles' either. I've already put hard challenges in my game, why compound them with additional, purely-dice dependent complications that hardly add any fun?
I can understand that. There are a couple of options here, including the Ranger taking the Sharpshooter feat (or whatever its name is). Then the cover bonus to AC goes away and he doesn't have to worry about hitting the ally. Or you can just skip it as you already are.
At my table, a lot of the best moments come from failure.
The TWF dex fighter rolling double 1s and closing her eyes and swinging her swords wildly as she passes the wolves invoking opportunity attacks.
The Half-Gnoll Paladin throwing a javelin at extended range and rolling double 1s on disadvantage, then critting the Tiefling Wizard with the errant javelin.
The Tiefling Wizard accidently placing the corner of wall of fire on his new cart.
The Human Cleric getting a 3 on his persuasion check to stop a raging half-orc from fighting anymore (actually the half-orcs failure; he rolled a 2).
Of course, a lot of great moments come from success as well.
An evil wizard uses telekinesis to lift the Half-Gnoll Paladin 20 feet over the entrance of a 40 foot spiked pit trap and lets go. The Halfling uses her reaction with a granted inspiration point to run up and cannonball the Paladin of course so he doesn't fall in the pit.
The TWF dex fighter double crits and turns tough zombies into flying bits.
The Dragonborn sorcerer rolls almost max damage on a lightning bolt that skewers two invisible stalkers.
As long as the fumbles/failures are few and far between and
fun, my group seems to have a good time with failure.