You can just say you are opposed to the D and while you will not stand in your path you will not be able to help her with it either.
Im not even sure i would say "I'm opposed to the D". Just refuse to help out with it. Hard to ever get her thinking SHE might be the one getting dumped if you tell her "Im opposed to the D."
Just my 2 cents.
H53/W51, R-ing 4/'18
"Do not arouse or awaken love until it so desires"-Sg.of Sg 2:7
"So oftentimes it happens,that we live our lives in chains, & we never even know we have the key"-Eagles III 1:3