Looks like internal reflections in your lens, accentuated by shooting into a bright light source i.e. the window behind the couple.
I may be reading too much into the picture, but if you overlay the image on itself, then invert it (rotate 180°), it seems the 'white patches' are formed by the shape of bright light is from the window and the guy's head!
You should be able to see this in your viewfinder when shooting, but most of us don't see it till later. Be extra aware when there is a bright source of light in the frame, or even just outside the frame. A slightly different angle would probably solve the problem, or just move them away from the window.
For now, if you want to bother, a little application of the clone tool in Photoshop will probably do the trick.