You should be truthful about previous relationships with your partner.
Jen is engaged to Toby, and he will be her second husband.
Jen wants Toby to stick around through marriage.
Jen tells Toby she's been married before, but that he is the one.
Toby asks Jen if she's ever been married, and she tells him no, thinking that the truth will make him flee.
Toby goes into his marriage with Jen knowing everything he needs to know.
Toby eventually finds out the truth and leaves Jen for her lack of honesty.