The ring disappears after use regardless if they accept or decline. The person you proposed to does not have the ring. You can try contacting the GM's to see if anything can be done, but you may be stuck married to that person. This is why it is important to chose wisely and why the game asks you to confirm your choice before the ring is used up.
DDT:(GS)Shannia - Cerberus/Phoenix | (GS)decoy - Serpent