I love flying Delta, but seat changes without notifications are quite common if you book your tickets in advance. My general philosophy is that I'm happy as long as I'm still sitting next to my other half & I'm still in the same class of service.

My other half HAS to have a window seat when we travel, so this sometimes is an exercise in creative patience. But so far, so good, although sometimes we wind up in bulkhead. (I hate bulkhead b/c I have to put my purse somewhere that I can't see it, but the window part works for my other half.)