This happens to me, too. I think it's a natural reflex - as the end of stitching approaches, my hand gets 'shy' about the needle and my guidance of the fabric disappears. I also had to stop looking at the needle, and actually watch how I was guiding the thread in relation to the edge of the presser foot. After all, the needle only goes up and down; it's the fabric that tends to move around.
I also discovered that, for me, the 1/4" foot without the guide blade allows me to really see where to guide the fabric. Seams are much straighter now. My sister uses the 1/4" foot with the guide blade, and likes that much better than the one I use. Everyone is different.