What might he have meant by “it feels so right!” during sex?

We’ve been dating about a year, are not I love, probably slowly drifting apart now if anything as I’m now keeping my options open and have advised him to also (even though he says he won’t he probably will). I feel like he tries to make me a bit jealous out in public and always looks over my shoulder to see who I’m talking to when texting now. He’s said he can’t commit but is really happy, to me it’s just becoming uncomfortable. Any thoughts on what’s happening?

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Just to clarify, he said can’t commit yet but doesn’t mean he won’t, although in all honesty I’m not holding my breath)
What might he have meant by “it feels so right!” during sex?
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