Lust and the Flesh (1965)

Bob is a struggling artist who is dependent on his wife Helen for money as well as deal with her nymphomania. Bob and Helen pick up a couple, named Myra and Mike, at a sleazy bar during a weekend vacation to coastal New Jersey. Helen and Mark hook up immediately, while Bob has fallen head-over-heels in love with Myra as they take a walk along beach sand dunes. Helen invites a group of wild friends over at their hotel room for a party of debauched activities. Bob tries to convince Myra to run away with him, while the abandoned Mark meets and hooks up with Helen's friend Ilsa.