Sentence 1: Cathy wanted to go to the beach. 
 Sentence 3: The day came for them to go 
 Sentence 4:  Her husband didn't want to go anymore 
 Sentence 5:  Even though he was supposed to he didn't go and she went alone 
 Option 1: She planned it with her lover that she was having an affair with. 
 Option 2: She planned it with her husband.