Verified answer

A virgin, by the normally accepted definition, is a girl who has never had a man's penis in her vagina. A strap-on is _not_ a penis, any more than any other dildo or other foreign object is a penis. The use of a strap-on might be said to involve two girls in a _parody_ of the procreative act, and thus a _parody_ of the girl so penetrated loosing her virginity, but parodies of things are not the things themselves.

The things you do with your girlfriend mean what they mean to the two of you, but nothing you might do would mean loss of virginity unless you were using the word "virginity" in some extended way that departed from the standard meaning and had a special meaning to you and perhaps some group who shared that special usage.