The answer is no. Your boobs might change shape and size very slightly but this is normal and has nothing to do with your boyfriend touching them.

No way. If you or anyone else touches your breasts, there is no way they can become smaller because of it.

WHy is this even a rumor!? Where did this come from all of a sudden? She's the second girl who's thought that a boy touching her breasts will make them small/ugly/give her cancer.

If you touch your boobs, nothing happens, so why should someone else's hands cause them to shrink? I'm not angry at these girls, I'm angry at whoever planted these ideas in their heads, or whoever failed to properly educate them about their bodies.