@jim 1968,
Many of us, male and female, are socialized to not be deliberately rude to others.
That sometimes makes it difficult when someone's taken small steps over the line, and then bigger steps, and then it's oh ****, I'm in something I'm not good with.
Watching for those first small steps over the line is the key.
Talk to her. She may be a good **** buddy if you are 100% straight-up about it - and hold the line to that. If she's not in the place for that, someone else will be. There are women out there who don't want anything other than someone to have sex with regularly. Not all of us are looking for someone to cuddle.