My fiancé

I need your honest opinion... my fiancé and I have a 1 year old baby girl, and so does my sister. Recently my sister got separate And well you know you invite your family to help them be happy, so I invited her out. My fiancé rented a room at a hotel with 2 beds. We went swimming had a good time then it was time for bed. So, we all went to bed, I and my daughter and everyone else fell asleep as well , I got up to the restroom and see my fiancé in his boxers. How or what should I think or feel? If I did that with his brother be im my underwear i would get in trouble ..