I work in a small company in the US - myself, my boss, and a marketing intern. I have worked at the company for four years, marketing intern for 8 months. It is an independent software dev shop. We make software for other companies.
About 3 months ago, I mentioned to my boss that I was leaning towards leaving, because I had been there for a while and I didn't see much potential for future growth (and that it might limit my future career) and I also wanted a change of scenery. I had been thinking about this change for quite a while (about a year).
My boss offered me a decent raise which for the time being I have accepted, though I expressed my reservations about the job at the time. He seems to feel this has made everything fine and even discussed how we'd be working together years later. However I still feel that there's not much growth potential, and I honestly think (based on different salary websites, recruiters, and job listings) I could probably get a higher offer than I was given.
Considering it is a small business and this feels as much like a personal matter as a business matter - how do I amicably cut ties? It doesn't help that I do the majority (I would say 90ish %) of the coding for the company so I feel like if I move on, he won't have anyone to pick up the burden (he can code, but he's always busy with business stuff) at least in the short term. Do I just come out and tell him I want to leave and give him some time in advance (say a few months), despite the raise? Obviously I wouldn't leave until I actually have a job in hand, but considering my field and the demand, I don't feel that will be very difficult.