Is the Kind of Love Described by Ruth in “The Silent Patient” Possible?

Could it be that saying “I love you” to a person is promising the impossible?

I was reading “The Silent Patient” by Alex Michaelides, and this quote struck me:

“Love that doesn’t include honesty doesn’t deserve to be called love”

If this is the case, what are we then doing with cheating partners? Cheating is dishonesty, right?

Does that mean we should leave once we find out our partners cheated or is cheating? What if they made a mistake? What if they apologize and are remorseful? Does it mean because they were dishonest, they don’t love us?

Or is it just the fear of being single that keeps us with them? Maybe not just the fear of being single. Perhaps we have kids with them, and we don’t want our kids to grow up without a complete family. In some parts of the world (my part of the world, for example), there’s a stigma of children that grow up in single-parent homes. Maybe we don’t want our children to experience that because of a few cheating experiences. Or perhaps we are scared that the devil we know is better than the angel we don’t? The angel we aren’t even sure exists?