dirty talk

i used to be really good at helping my boyfriend jack off. id write him sexual stories and id be into it too and i felt creative but for some reason I can't seem to get creative anymore? i never know what to say or write and im just not into helping him jack off. he's getting upset because he thinks im uninterested but I'm completely interested and love him to death I just don't know how to get into the mood to help him anymore. help?