Staying faithful has numerous benefits, including:
The film excels at depicting human self-sabotage. The main character’s insecurity is the true villain of the story. By orchestrating a scenario to test their partner, they actively destroy the safety required for love to flourish. It serves as a cautionary tale: If you look for reasons to leave, you will always find them.
The title itself is a command and a paradox. It suggests that the only way the protagonist can remain "faithful" to their current partner is by using someone else as a buffer or a test.
On the other hand, infidelity can have severe consequences, leading to feelings of betrayal, hurt, and anger. It can be incredibly difficult to recover from an affair, and in some cases, it may even lead to the end of the relationship.