I get your question.
If a guy asked me to be his girlfriend before we slept together and we were not sexually compatible than it would seem really jerky to break up with them after.
If he asked me to be his gf before we slept together and I had a conversation with him saying I would not date or pursue others until we knew the compatibility was there than it's an understanding that we are exclusively exploring compatibility before putting a label in it.
That way your now not introducing that other person as a gf/bf to family, friends and social media. Your not getting broke up with after.
It can be at that point I was dating someone but it just didn't work out.