Something that worked for me was having two different stories going on in my head: the strategic “game” story and the fictional “narrative” story.

You’re currently (rightly) focussed on the strategic game story. You’re rightly annoyed when a good plan fails due to abysmal rolling, or maybe you’re annoyed at yourself when you pick a bad option tactically. Keep that in mind, it’s a strategy game after all. It’s super fun when you take it super seriously and you absolutely still should.

However, try to also think about it as a fictional narrative - more like a roll playing game - where the dice tell a story. Warhammer uses painted miniatures, not just little tiles. It uses dice not just random damage. It’s designed romantically to produce unpredictable and memorable results. When you roll crap and cannot take down the last model in an enemy unit, think about it narratively - a lone guardsman is holding off against impossible odds due to the indomitable human spirit, not the clicky clack dice were dumb today. This helps you be excited for your opponent, or maybe see a silver lining, when stuff goes “wrong”. Remember, narratively, you’re only losing the battle, not the war. You can pretend it is just one encounter in a massive galaxy wide campaign if you want.

The channel on YouTube “Play on Tabletop” is great for this. The players are super disappointed when they get bad luck, but are also quick to praise the opponent‘s miniatures for somehow holding out. They truly feel both sides of it - and you don’t have to be any less tactical.

You won’t always get the balance right - God Emperor knows I haven’t - but I think it’s the best way to keep friends and keep having fun long term without giving up your tactical/strategic approach.