You only presume to know. You have no idea what a persons motivation or reason is. The attitude you're displaying here is not one of clear thinking and reason but one of lashing out at people for not behaving as you believe they should because their actions hurt you. And yes, that sucks and it hurts, but if that is the choice they make it's their right. And that has nothing to do with their being Christlike or not.
But, again, you don't know the reasons and motivations. You're just responding with emotion.
Where do you have the biblical evidence to show that God is not happy when people move on in their lives, and in the process leave others behind? Because if you can't provide scripture to back this up then you are speaking for what God has to say out of your own voice and opinion, not for any fact you can prove.
God brings people into our lives, some for a long time, some for a short time. Or as one of my friends on here puts it 'some people are only in our lives for a season'. Perhaps God is the one that has caused this person to move on. Until you can get inside their head and know exactly what they are thinking and feeling (not presuming to know) you have no idea what their reasons are. And still no scriptural evidence of it being wrong.