There are times when people we love hit a rough patch. As a result, their behavior totally changes. Our initial reaction, our impulse, tells us to get upset.. not to accept the change or the way they distance themselves, lie, or even deceive us. "But why didn't (s)he come to me? Why did (s)he not tell me?"
When someone you love is going through a difficult time, it's important to check your emotions at the door in order to help them. It doesn't matter how what's happening makes you feel. You're not the one dealing with this situation. What matters, is that the person you care about is in trouble. Focus on them, their problem, and how you can help them out.. even if it means leaving them alone to sort things out.
When you want to support someone, you should do it wholeheartedly.. or not at all.