If you have a much better opportunity, do it - it's not unethical. Your boss may have expected you to stay for many years, but they also know not everyone does.

If you have a much better opportunity, do it - it's not unethical. Your boss may have expected you to stay for many years, but they also know not everyone does. I've done it in the past. My boss was dissapointed, and I felt bad for about 10 minutes. I would have felt bad for years if I'd stayed. If you're concerned about friendships at work, fair enough. If you stop working daily with people many friendships will become less active. However, you can still stay in touch with people. And in 5 or 10 years, when most people have moved on from both companies, you'll hopefully keep a few friends from both. As for the impact on your career: don't worry about it. Nothing wrong with changing to a better job. If anything, I'd say it will improve your resume (as in: worked for google then for facebook, awesome.)