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?
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.
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.
Changing hobbies is not the same as trying to change what you did for a living for the past decade.
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.