I've worked for some genuinely great companies (and some not so great) over the course of my career and companies change, just like people. A great company you

I've worked for some genuinely great companies (and some not so great) over the course of my career and companies change, just like people. A great company you joined, might not be so great in 3-5 years and there's rarely much one can do about that. If it's no longer a good fit, it's not disloyal or unethical to move on.