Best way to end a casual dating relationship?

we see each other 1-2x a week, text pretty much daily at his initiative, and phone talk sometimes too.

but it isn't going anywhere serious.

i don't even know if I really want to end it either. in a way I should because he's a jerk and I want a boyfriend and he won't be one. on the other hand I have fun with him, I never let myself have fun, and I just...can't let go because I'm so hot for him that it's not normal. and I am single and free to meet other guys even with him.

when we don't talk for a few hours I'm making lists of why I should end it but I just don't want to right now, truthfully. he just frustrates me so in my frustrated state I think about dumping him.

but, how do I end it? what do I say? I guess the best excuse is that I decided I want a serious relationship and I know he won't give me that?

or that I worry that if we have sex I'll get attached?

i don't think the truth, which is that he acts like a pompous a**hole and frustrates me, will fly? or can I rephrase that? help?
Updates
+1 y
i can get attached yes but I really like being with him...he was sweeter at first and I guess now that it's been well over a month and we talk a lot he's getting "comfortable" and is confident that he has me. that's what makes me want to end it, so I guess I could tell him I'm thinking of walking away because he used to be nicer to me and now he isn't, but what's a good way to communicate that?
Best way to end a casual dating relationship?
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