I guess I'll be doing the same when boyfriend and I move to the UK. His parents are obviously not looking forward to us moving, but aren't kicking up a fuss. How is she reacting exactly? Is she making you feel guilty, or is she trying to be positive about things?
I think that often if your parents are in a good place themselves, then they tend to feel happy and excited for you. But if something is missing in their own life, then it can be harder. But the important thing is, you shouldn't feel guilty about it. You have to make the best decision for yourselves. Adult children need to be able to spread their wings, follow their hearts and dreams and build the life that they want. I realized a long time ago that we would never be able to please everyone.
Honestly, I think that you and his mom can make the best or the worst of your situation. There are plenty of families who live in the same town that have bad relationships, and many who live far apart who have good ones. It's all about what you make of it. Skyping, making an effort to visit, and keeping each other up to date about your lives are important. I've been living in the US for 5 years, and I still feel very much part of my family. But I have also put quite a bit of effort in. I have visited them at least once per year, and my parents have been over 3 times each. I phone my mum every week. I do miss them, and there have been a few bumps along the way, but I think overall we've made a pretty good go of it. I hope we'll do the same with boyfriend's family once we move.