Hello virgogirl37; trust me if your Gemini friend said that they were going through a shift and didn't explain themselves, then there are two possible explanations:
1.-They were truly going through a psycologically tough time. They needed space to see their problem from a neutral ground. Telling you how they really felt may not have helped. It may have made them get a temporary solution and not one that best fits them.
2.-They may not trust you with the information in their head; or might have felt that you won't fully understand; they might even know what answer you would have given them;Last but not least, they may probably have kept information from you, so as to protect you.
You see, Geminis, just look at life from a all perspectives and not just from one...its our curse and our blessing.