has a bad temper

That's not necessarily a red flag IMO. Perhaps a yellow flag.
Let me explain; I used to work as a bouncer in a bar/café a long time ago (late-1999) with a guy who was the stereotypical "always-angry" looking dude who kept his communication to the bare minimum. Almost caveman-like.
I also met a very sweet girl there, and had few dates with her but I didn't want to go further with her.
Turns out these two have been together since then to this day. They're happy together.

It's all about the chemistry. A "bad temper" is in the eye of the beholder until someone becomes violent.
My parents could have absolutely huge blowouts when I was child. But I never, ever saw/witnessed any violence or throwing stuff or even grabbing. It was just words. If my dad raised his voice my mom would raise hers higher. I guess my dad would realize the nonsense and tone down, as did she. They just loved each other that deep.