Lorraine is always the forward one, so I thought it made a lot of sense for her to get into the first frisky action she saw going on at the party. And as they've shown before, they don't mind sharing.
And I wanted a little moment of hesitation and worry as Patty waits for Trevor in the closet. She's been in there for a bit now, missing out on Olivia's big "display" and argument with Martin. So I thought she'd be a bit worried and close to giving up at this point.