Starting to hate myself

I'm 36 now and a couple of weeks ago I started to realize that I've changed a lot in recent years. I have a good job in a normal company, have a girlfriend with whom I kind of had a good relationship (although now I'm not so sure about that anymore). But it's not like that, everything is going wrong, everything is on automatic. Yesterday I had another scandal over nothing with one of my friends. And it finally dawned on me that I have become more and more irritated by habit, like a robot, like a machine, like some kind of mechanism. And I don't like what's happening to me. I'm beginning to hate myself little by little. I understand that in these situations it can be useful to consult a psychologist. My question is more about something else, and maybe a little strange. What can a psychologist give me in my situation? Advice about how to get myself in the right frame of mind? Or will the psychologist give his assessment from the outside - what is going on with me? I just don't understand how psychologists can help in a situation like mine. I tried to be as frank as I could. I would be grateful if you could answer.