Why do some men chase sex so desperately but not want a relationship afterward?

I can’t understand men. One men I slept with, after that I found out he flirt with everyone. He took my virginity but didn’t value that and immediately started looking for other girls. One girl he flirted with said that he’s weird and creepy. I would understand if he was popular but he’s not. Many girls don’t like him. But still after having access to me instead of becoming good boyfriend he’s looking for other girls? I mean i don’t think other girls he is flirting with prettier, also we all Asian, so I just don’t get what is the point being so desperate about sex and then not dating girl that you had sex with and looking for other girls? Like why you’re so desperate then? What’s the point sleeping with someone and flirting with everyone if you don’t care about after you getting it? If you’re so desperate to sleep with someone why you don’t keep in touch with one person that showed you interest? And he is 10 years older. I don’t understand. Men are so weird. I want love and relationships if someone will give it to me I will not like for someone new, but men still looking for others after getting what they want?
Why do some men chase sex so desperately but not want a relationship afterward?
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