Not all can walk away and separate sex, some do want love or some form of connection and won't have sex without it, others might like casual sex for a while, sometime a long time then something changes. It's not as straightforward as we might think. My experience is that quite few men do want a relationship, don't like it if there's not follow up and do want a relationship after a shag.
I have found myself in this situation 4 times. The first 3 have all been purely based on physical / sexual attraction.
One girl fizzled out because I could sort of sense she was realising she should of been earning money for it.
Another I simply got bored and the girl didn't bother chasing me up on my vanishing act so I assume she wasn't too fussed either.
Another girl i didn't even pay for. We exchanged texts and built up a rapport and then after swapping photographs she just asked me to come see her with a bottle of wine and to she what happens! That ended similarly to the second girl.
On all three occasions the speration between sex and a relationship was clear. The reason I mentioned my age was because I though this was just a case of young people messing around.
The 4th girl I seen was the hectic case. I booked her and after a meeting I sent her a text saying how much I enjoyed myself; she replied something along the lines of "come back then"... I told her I couldn't afford her but she wanted me back anyway.
This girl used to work out of hotels and every lunch time she'd cancel whatever she had on and let me come see her. By now I'm thinking I'm some sort of stud, this is the 4th time this has happened to me, I must be great in the sack, right? Anyway, I asked her, "am I the best you've ever had?" The answer was a resounding 'no'. She just liked me the most for casual sex, she liked my personality, thought I was a lovely guy.
From there things sort of changed. Her attitude to sex was different; she'd take the condom off me for oral, she'd let me cum in her mouth, for foreplay she'd rub herself on my dick without protection. It was all stuff that I sensed she was doing not for sexual gratification, but because she like me. The lines were 100% blurred. There was even one occasion where I was practically about to go bareback but just resisted at the last moment.
I felt shitty after a while because i could see this girl was head over heels in love with me, whilst to me, it was just great sex.
Eventually after me cancelling to see her a few times she just blew up on me and that was that. I could tell she was fucked off withe because obviously by then she could tell i was only casual with her.