Lori likes to enjoy the simple things of life, like sunbathing while laying on the grass. The warmth of the sun rays remind her of Johnny's hugs and caresses, one of her main sources of happiness.
If you're wondering why she's naked in the open, the truth is she doesn't mind at all. Being herself a druid and raised in a different environment, she feels comfortable hanging around without clothes. She's a bit wild, but that doesn't mean she's not smart. Due to society pressure, Johnny encouraged her to keep her robes on when they were with friends or in any social situation. However, Lori knows she can be herself around Johnny, so if she wants to take off her clothes, she just does it. Johnny enjoys the view anyway and knows he might get something else later.