Oh, love! How marvelous you are. How you make the world bloom around us. Without you, our live would be awful. Ha! Pretty much every character in this story would tell you the opposite. To Glaucus, Scylla, and Circe it's love itself that makes life so bad.
Glaucus is totally happy being a sea god, until he sees the gorgeous Scylla and becomes tortured by his love for her. Circe gets her feelings majorly hurt when Glaucus rejects her, which isn't fun even for a sea witch. And poor Scylla gets transformed into a horrible monster, all because she gets caught up in a love triangle she never asked to be part of.
In the tale of "Glaucus and Scylla" we see that sometimes love isn't always a bunch of fragrant roses that makes your life better. Sometimes, it's a clump of stinky seaweed that ruins your life forever.
You've got bunch of transformations in this story, for sure. First, there's Glaucus, who starts out as a simple fisherman, only to be transformed into an immortal merman, after he eats some magic herbs. Glaucus' life goes through a pretty major sea change after this. Not only is he no longer a mortal, he must now spend every single second of his immortal life in the watery world.
Glaucus is transformed again when he spies Scylla naked on the beach. This time, though, he isn't transformed physically; he's transformed by love. He goes from a content life as a sea god, to being a tortured soul, desperate for the affection of the gorgeous nymph.
The final transformation in the story happens to Scylla, after Circe's potion takes its evil toll. Scylla goes from being a gorgeous sea nymph to being a horrible monster with a pack of snarling dogs sprouting from her lower body. This physical transformation also transforms Scylla's personality, and she spends the rest of her years, bitterly devouring whatever sailors get up in her grill.