Preaching Up VS Preaching Down
It might seem like a paradox that true love can only be revealed by sin, but this is an actual case to a degree. We can share our love for someone by saying it or doing something kind for them, but ultimately, true love can only be revealed once it's put to the test.
It's easy to love when times are good. It's hard to love when times are bad. When a relationship is out through the strain of one party doing wrong toward the other, this is grounds for where true love can strengthen or it can falter.
Both involved can see if they are willing to work through anything together or if they're only in it for the good times. We must not try to test love, but when a test comes, we must be ready to overcome sin by fostering true love.