Hi—I kinda went a little long here,,, sorry.
He needs to work on himself.
There could be many reasons he has a short temper. And many reasons why he needs to seek professional help.
Saying "F" you to someone is something most people only think- and maybe want to say it, but they have something in their brain called an executive function that stops them. I feel like telling my boss that, for example, but know if I do, I will be fired. I feel like telling that to my kids when they are being extremely difficult, and I am tired, etc., but I don't for obvious reasons. I have never said that to anybody for all the reasons in the world. And beleive me, I have had many good reasons to, many great excuses, but I still haven't been able to do it…even when I was drunk. (Alcohol being the great deinhibiter, but then I don't drink as I might say something I regret later.)
A reason someone might say F is s/he might not have any or little empathy. A person that could say that obviously can't put themselves in another person's shoes. That is scary, as people without empathy need a lot of help and have to learn to adapt in many situtations. It is almost impossible to have a relationship with someone with no empathy. And sadly, empathy is developed early in life, and it is rare that it is developed late in life. As much as a person wants to learn and wants to change, my guess is it is pretty much a losing battle.
Others who would blurt something like F you might have a severe case of ADHD- but again, this person needs to learn strategies on how not to blurt, maybe take appropriate medication, see a specialist to help them cope.
He could have an anxiety problem… overly stressed and in a state of flight or fight. He then would need to learn how to handle his stress, and find creative, mental, intellectual and physical ways to prevent and allivate stress, as opposed to telling people to F themselves, or what have you.
And he could just have a short temper becasue no one has called him on it, and therefore he gets away with it, and he must get something out of it. But then, he would need some anger management or something.
Whatever the case, if mentioned above or if something elese, it is his problem to deal with. He needs to fix it, and it might be hard if you try to help fix your torturer. 10-1 he won't stop.
I tried with my ex for 18 years. When I left, he just found someone else to say F you to, and then he dumped her and is onto honey number 2, and honey number 1 is chasing after him, as if she hadn't had enough. She thought she could change him (she was with him for 3 years.) I was relieved that she took him off my hands as he was quite jealous, and beleive me, after him, I don't think I will be with anyone for awhile yet.
So in a nut shell, how do you deal with a short tempered boyfriend, you fix your own life, detach and hopefully he will change on his own. It is up to him.
If you feel alone, think of what yu would like that special someone to do for you, and then do it for yourself. You want a massage, then go get one. You want the tap fixed, hire a plumber. There are wonderful amazing friends, family, neighbours that will fill the gap, fill the loneliness. Volunteer, spend more time with your kids, your pet, an elderly aunt. Often these guys fill soooo much there is a giant gaping space that gets left when they leave, or you leave, but over time, you can chose to fill it with wonderful people, animals, events, charities, causes….
All the best