Sea-nymph mother of Marinell, Cymoent (called Cymodoce in Book 4 for unknown reasons) takes neurotic parenting to a whole new level. Spending pretty much her entire time in the poem worrying about her son Marinell, she inadvertently ends up furthering his suffering rather than preventing it.
Because she misunderstands a prophecy that says Marinell will be hurt by a woman, she raises Marinell to loath romance and love entirely. Unfortunately, the prophecy is actually referring to Britomart, lady-knight, who does seriously wound Marinell, leaving his mother in charge of finding a miraculous cure.
Once cured, she refuses to let her son leave her home for fear of another injury, which, you probably aren't surprised to hear, doesn't really go over well with her young and hot-headed son. When he does finally fall in love with Florimell, Cymoent is again a nervous wreck, but finally does her son some good when she secures Florimell's release from Proteus.