One of the first times I realized I was turned on by my wife being exposed to other men happened when she went to visit as friend from college. My wife had a conference in Houston and her friend Brenda invited her to stay with them instead of a hotel. I met Brenda a few times as a cute coed but had not seen her in years. When my wife got home a few days later she said she might be interested in installing a hot tub, something I had been pushing for but my wife was against. I asked what made her change her mind, she said Brenda and Roger had one and it was fun to unwind after work soaking and sipping on wine. I asked her what she used for as swimsuit, I knew Brenda was quite a bit bustier than my wife, she said "I didn't, we always skinny dipped, only nerds wear a swimsuit in a hot tub." "Where was Roger?" "Sitting there with us of course". Instant jealousy and instant boner. We had played strip poker with other couples and even skinny dipped, but always together. The idea that another guy got to enjoy seeing my wife nude and I got nothing was unsettling and I was upset for a while. My wife said "I didn't think you'd care since we've done it before." Then the lust set in, I told her I was very conflicted about this and I made her go over all the details, did they touch, did he see her pussy too, did she enjoy seeing his cock, did he get a boner? Yes to all questions but nothing sexual happened, touching was unavoidable in a small hot tub, of course he got a hard on, he was sitting next to 2 naked hot women. Of course I wanted her immediately, especially when she told me how exposed she was when she got out to go to the bathroom. There were other similar occasions, but I remember that first time.