Sentence 1: Mary contracted a sexually transmitted disease from her girlfriend. 
 Sentence 3: Her girlfriend swore she hadn't been cheating on her 
 Sentence 4:  When Mary confronted her girlfriend about the STD, she confessed 
 Sentence 5:  Mary broke up with her girlfriend for betraying her trust 
 Option 1: She was furious and thought she must have known she had it. 
 Option 2: At first she didn't understand what had happened.