If you care that much, just stay friends. If you both actually care you two can find a way to do that
Don't do that.
If you stay part of her life when you're emotionally tied to her, you'll be on her hook. Any time she seems available you'll want in.
Plus when you find out about her next bf and her you'll die and deny it. When you hear about them having sex it will kill you. Don't be her friend when you're emotionally vulnerable it doesn't work.
The inverse is much more likely to be an issue. ---
"Kenan & Kel is what made me realize I wasn't racist." ~ NewportBox100s