why do ppl do this :/

i was SO close to getting my dh (zebra stripes iuh marwari) and they asked if i could add bc i was giving a tiger striped marwari as a swap and i added in a iuh mustang bc they said that was ok! they went thru with the first part they even accepted first but then at the last 5 seconds they left. if u dont want a offer just say nty instead of getting ppls hopes up