For me it was the first time my wife saw me wearing a bra. I was 27 years old at the time and we had only been married about 10 months. A few months before, my wife had discovered my only article of female clothing, a bra, that I had hidden among the male clothing in one of my drawers. Not surprisingly she reacted badly to the discovery, including tears, anger and all the normal questions. In the intervening months, she said little about the bra, but at least said I could keep it.
On this particular evening, we were watching television and cuddling together on the couch. She was caressing my chest and playing with my nipples, something she knew I loved. I made the comment that if she kept doing that I was going to want to wear my bra. To my amazement she said go ahead.
I went back to our bedroom and put on my bra, filled out the cups with some of her panties, and replaced my shirt. When I returned to the living room I was both terrified and excited, but mostly embarrassed. She quickly eased my fears and we began cuddling and caressing again. After a few minutes she took me to the bedroom where we completely undressed, except for my bra, and made love.
We have now been married 35 years and since then she had seen me countless times in bras and other items of lingerie. Still, that first time remains my fondest memory ever of crossdressing.