I'm also not trying to sound dismissive or condescending, but it really seems weird to me that if somebody says they are have been doing something for 20 years and now they are bored of it, then they should consider seeing a therapist?
I mean, there are plenty of things I used to like that I don't anymore, should I go see a therapist every time my interests change?
I think it's more about your intent. I'm not too bothered I don't care about soccer any more, I'm not after therapy to change that.
In this case though, I see someone who badly wants to be enjoying programming, but for whatever reason they don't understand they don't. It's probably a good time to talk to someone. Usually I'd start with my girlfriend, maybe my mum, perhaps take a few weeks off and then see how I feel. If that doesn't sort it, I'd probably want to talk to a therapist.
It's true this kind of stress and feelings are universal, but doesn't mean it's not a potentially serious psychological concern. Parents who feel extremely overwhelmed with lots of young children in the house are understandably stressed out - and yes, should be encouraged to consider therapy to help them manage.
I would recommend reading munificent's comment above about therapists as "mental trainers." I think everyone should consider seeing a therapist at least at some point in their lives. The idea that therapy is only when something is medically wrong is at best misguided and at worst dangerous.
When I suggested OP considers therapy, I didn't mean "uh oh, sounds like you're clinically depressed, DSM-V states that a loss of interest..." And the word "consider" is doing a lot of work there. OP's brain is clearly trying to tell them something, and having a knowledgeable certified professional to talk things through with is simply prudent when it comes to something as profound (and risky) as reconsidering your career.
Careers are not cast in stone. Some people do change their careers if they realize that there's something else that they'd really rather be doing with their lives.
I've met an artist who became a doctor, a lawyer who became a stockbroker, a software developer who became a full-time professional musician, a professor who started a hedge fund, etc.
On the other hand if you are changing field because you are unhappy with your current situation it is relevant to ascertain that your current field is part/cause of the problem.
I mean, there are plenty of things I used to like that I don't anymore, should I go see a therapist every time my interests change?