I am looking for a book that was probably published in the early 1980’s or so.

It is a science fantasy book, set in a different land.  The main character is a woman, who is a “witch” (wise woman) and she is married/consort to the local lord, which isn’t as glamorous as all that – the lord loves to discuss pig breeding with the farmers and he does wear glasses (I believe)
There is a dragon (and old one – could be the last dragon in the realm) who is awakened and she & her husband are tasked to kill this dragon.  She has the power to understand the dragon and the dragon falls in love with her – she is able to transform herself into a dragon and she loves it.  But then she realizes the life she had as a woman and transforms herself back to a woman and goes back to her family and life