Same Ward
The key here is communication, between you and Zach. Tell him you're frightened. It's been my experience that that sort of transparency is far more appealing than, say, the cold stiffness of putting on a brave face.
I think the two of you are good together. There's no reason this should be a detriment to what you have. In fact, providing you two can get on the same page about this, it might bring you closer together.