I'm not namechanging because this isn't about me - it's my friend and her DP: they are not parents, won't be on here etc.
Basically he is in an almost permanent bad temper, not just directed at her, when something annoys him everyone around gets some. He uses very threatening language (but I have never known him actually raise a hand to anyone and she would have told me - and got rid of him - if he had actually hit her.)
He does have good points, can be very helpful and kind and is excellent at practical support (he's always the one who will drive people around and help them move house etc as he has a big car; he's good at DIY type things and willing to do them for other people without expecting payment). He was always grumpy but has been getting worse lately.
Has anyone any advice other than 'tell her to bin him'?