I met my husband’s younger brother when I was dating him and his brother and I got along together immediately. Then we got married and his brother being a college student back then, lived with us. It used to be me and my brother in law for most of the time in the house as my husband travels a lot for his work purposes. My BIL and I basically talked about anything and everything as were like friends and I found out that he was a virgin and was having hard luck with women.
So I asked him whether he would love to try it with me or not. I don’t have any explanation to why I did so, despite being married. He seemed a bit hesitant but when I asked again, he was in. Long story short, he lost his virginity to me that very evening. Neither of us felt any sort of guilt post sex and we decided to continue this.
Since we had ample privacy we had sex whenever we wanted but behaved when my husband was home. The dynamics never really changed between us as I was still his sister in law and he was my brother in law and we were never lovers. Although he used to tell me that I am ‘training’ him to be a better lover and husband.