We know that the Sota is a woman who is suspected of committing adultery. This claim is based on the fact that she was caught in seclusion with a man who is not her husband. She has to drink the potion to determine the truth - did she commit adultery or not. If she did, she is cursed. If she didn’t she gets huge Brachos: if she was barren, she will bear children. If until this day, she had only girls, she will give birth to boys. And so on. The question is - why does she get a Bracha if it was found that she didn't commit adultery. The fact is - she secluded herself with another man. Shouldn’t she should be punished?
The Torah however, looks at it differently. This woman was on the way to do an Aveira with the man. Not only was she on the way, she almost did it. She was alone with him. She was so close to falling - and she said no. She had the power to say I'm not going through with this. I am going to stop now. I don't care how far I have fallen. I'm with you Hashem. No one else can see me doing this apart from you.
Sometimes we feel that when we slip - it's all over. The lesson of the Sotah is that even after one has slipped, when he/she could go all the way, all is not yet lost. When we slip and we say I could go all the way but I am going to hold myself back, it could be greater than never even slipping.