I think this is a key verse in understanding the fulcrum of sin. If you read over the chapter you can see that this plunge into adultery was not a sudden inspiration. It seems to have been planned and the plan was followed step by step. In a very real sense the sin was in the intent. Jesus makes that clear when He talks about what is going on in our hearts.
(Mat 5:28 KJV) But I say unto you, That whosoever looketh on a woman to lust after her hath committed adultery with her already in his heart.So intent is important but there is something about the moment you commit yourself by action.
Until you act the sin is between you and God. Once you put it in motion you bring others into the equation. In this verse the other party was just as guilty but what about the husband who is away on business. When you act there will be consequences. The conclusion here is that the man is now dead. His actions brought fruition to his attitudes.
So? Be alert for the downhill journey. It may start very mild but will eventually begin to speed up. It is much easier to grab the rail in the stairway when you first feel insecure than to wait until you are flying through the air. God forgives but we might get to the point where we can’t repent.