Why might someone marry for convenience or societal pressure, and what are the signs this is impacting their marriage?

What role do instincts and emotions play in our constant pursuit of what's beneficial, and can we trust them?
What are some movie clichés that make romantic breakups seem unrealistically easy and drama-free?
Do you think a person should act like themselves even if the other side doesn't get them or should they mirror the other person's act?