This is a long as fuck post that tries to dispel some myths guys seem to have here:
There's an implication that if a girl is coming over to your place, you are going to have sex with her. She knows this. You should know this. Whether you can actually make it happen is on your shoulders - that's your job as a man/PUA.
If a girl agrees to come over, ever, unless she is ENTIRELY naive (unlikely except with very religious/sheltered girls, or very young (I'd be surprised if any girl over 18 acts this way)), she expects you to try to fuck her. Not trying to fuck her or at least escalate on her will be viewed as weakness. Period. If a girl comes over to hang out at your place privately and you don't kiss her, you've fucked up, no bones about it. Attempting and failing will be viewed better by the girl than not trying at all. Remember that, and internalize it into your very being.
The vast majority of girls don't expect a relationship out of this - they're open to it, but it's more of a, "Let's see where this goes" type thing - remember, to the girl, you have a high possibility of sucking balls and she has no desire to be attached to a shitty guy, and remember, she has thousands of more options bugging her than you do, if she's even remotely attractive.
ONCE A GIRL FUCKS YOU/FOOLS AROUND WITH YOU A FEW TIMES, THEN they might want a relationship. In my experiences this happens after 3-7 hang-outs with physical escalation (not necessarily sex, but at minimum fooling around).
You can counteract this by making it clear you don't jump into relationships - you have to make the distinction of liking her, while not wanting to be committed to her. The relevant PUA concepts would be "qualification" (making the girl feel desired by you), and "managing/establishing expectations". For a recent example:
I met a girl (former stripper, though this works on non-stripper girls too) a couple weeks ago at a bar. I invited her over to my house to make me cookies and to drink wine. We ended up screwing around, though not fucking.
I was very clear about who I am - I don't commit easily, she probably won't get me to commit. I mentioned how I'm planning on partying with the college girls when they get back on the campus I live near (I'm a 29 yo professional FYI). She said she doesn't do things except with guys that go for commitment. Again, listen to what the girl does, not what she says.
That's managing expectations.
For qualification, you still treat her like she's hot, sexy, fun. I told this girl I wanted to see her this weekend, and her first response was, "Oh but I thought you were going to hang out with the college girls" - my response? "Yes, I am doing that, but I'd also like to try to fit you in too".
This communicates that you don't need her at all, you have many other options, but you still like her, you're going to try to fit her in.
This sort of reaction is like girl crack. It plays into the girl fantasy of having a magical vagina that can tame the wild beast of a man you are. You can never let her truly tame you, but you can definitely play into the frame of you, the consummate player and lover, being drawn in by her charm.
Her response? A very playful, "I'm honored you're going to try to fit me in

" - it was half a joke, but half serious. She's absolutely down, and I virtually guarantee that if I meet up with her again (and we will, if I have time), we'll fuck.
That's how you have sex with a girl without commitment. Most girls aren't looking for immediate commitment - immediately offering commitment is a sign of weakness. And you can easily get around that by maximizing your value, and being clear that she's special, but you're specialer, and there are a lot of girls out there for you.
Note, this works better on girls under the age of 27 (and in the US, over the age of 21 due to access to bars/more guy options), because around the age of 27, girls shift into a more solid commitment focus. That being said, this can definitely be used with over 27 girls, and under 21 girls.