I believe that the movie you are remembering is Krull, a 1983 movie directed by Peter Yates. Krull (film - Wikipedia, the free encyclopedia
The lover would have been Ynyr the Old One (played by Freddie Jones). The lady in the spiderweb would be the Widow of the Web (played by Francesca Annis), who was an enchantress who loved Ynyr long ago and whose terrible crime exiled her to live within the lair of a giant spider. Her giving aid to Colwyn (the hero) and his party caused the giant spider to turn on her, resulting in both her, and Ynyr's deaths.
Colwyn goes on to rescue Lyssa (his bride) and destroy the Beast that is threatening their land.
I hope that this was the movie you were thinking about.