My wifes old friend

Last summer my wife and I who are both in our 30s, spent a week at a nudist colony . When we got there the first thing we did was go to the pool. I was in a lawn chair and my wife was laying on a towel on her stomach next to me. Next to her was a 75 year old man sitting in a chair next to his wife. The old man had a great view of my wifes ass with her a**hole showing between her butt cheekes, He kept on starring at my wifes ass/a**hole. I thought it was kind of funny. Soon we began talking with this older couple and got to know them. I know the old guy had a crush on my wife. My wife saw this guy as a father figure and grew very fond of him.They began spending a lot of time together. I did not feel threatened because of his age and knew it was all very innocent. On the last day we spent there I was at the pool early that morning. The old guys wife came later and said my wife and him were watching TV in their cabin. She laughingly said her husband was going to miss my wife, and I said yeah. I knew he really liked her but I did not know how much.
A couple hours later my wife and the old guy came to the pool. The old guy had a big smile on his face and looked very happy. He seemed like a different person that day. He was diving in the pool and he was even playing vollyball. Later that afternoon his wife said everybody wanted to know what my wife did to him to get him so happy and perky. That kind of got me thinking.
The next day while driving home I demanded she tell me what happened and that I would not get mad. She said they were on the couch talking and he began getting tears in his eyes.
He told her how he was going to mis her, and how good and young he felt around her. He told her how his wife never wants to have sex. He also told my wife he was so attracted to her and could not do anything about it. My wife felt very bad and held him and carressed his head and told him its OK. She had tears in her eyes as she told me this so I believed her. What she told me next blew my mind. She felt she had to do something for him, so she layed on the couch on her stomach and told the old guy that he could f**k her in the ass so she would not get preagnant. The old guy was exstatic and told my wife she was beautiful. She said he then went on top of her held her tightly but gently. He had a hard time getting it in at first,but when it happened she said he had a pretty good hard on for a 75 year old. The whole time he kept on telling her how beatiful she was. They then clenched each others hands as he came inside of her. Laughingly she said he still had plenty of juice left in the old testicles.
When she told me this I was shocked but I could not get mad. I somehow felt in a way she did a good deed for the guy.

Is it normal to feel this way?