Wanted a job for the last 1.5 years, not anymore

I’ve been looking for a job since a year before my graduation. Approximately 1.5 to 2 years later, I now finally have a job offer. Now that I finally have a job I’m not happy. I’m confused. I have mixed emotions. I do agree that this may be somebody’s dream job, but I don’t even know if this is what I want to do anymore. Why did I have to struggle for so long to get what I really really wanted and now that I have it it’s not giving me any happiness.