Allow me to illuminate. Most clothing items in the program i use, DAZ3D, basically morph to the shape of the model. causing the huge crease in the cleavage department, among other problems. The only way to fix this that I know of is to simulate the characters breasts growing. So the clothing stretches with the expansion and looks more natural. I have slao seen it in many games and I try to do this as often as possible for my characters, so it looks decent. I miss it sometimes or don't have the time to run the simulation...or it just doesn't work.
For instance a scene I am currently working on, the top I have Chloe in won't allow me to run the fix. It just disappears when I try. So she may have a crease in a couple of pics she is in.
Hope that helps, and I am sorry if it annoys you, I can relate.