Hello, I am Rafael. Thanks for asking your question - I'm here to support you. (Information posted here is not private or confidential but public).
I am very sorry to know about your situation. I do not think you are "being too cautious" at all, but wise not pleasing him this easily, mostly because of how different if not incompatible it seems your value-belief system and ways to approach relationships appear to be.
Your words show you do not feel it's fine nor feel comfortable for a person to keep having casual sex with different people like he does. Your first communication showed it so clearly, I'd say shockingly, how this person's first priority and main concern around relationships is having sex, no matter how the other factors could play a role in it or not.
I believe sex is a core factor in healthy and fulfilling relationships, no doubt about it, but when it becomes distorted and downgrades or dismissed the other core dimensions of adult relationships, then things could get very dysfunctional, and for sure those people in your shoes, who care about feelings, romance, respect, sensitivity, commitment and more, get very hurt if easily expose themselves to people having such approach.
It is true that when there is not good sexual compatibility and fulfillment, relationships could not develop well, but this sexual fulfillment is much more than just the physical mechanic of sex, and requires a lot of empathy, personalities compatibility, mutual understanding, caring, open communication and other factors promoting real "intimacy", which is not only about coital sex, but about the whole multidimensionality of it,from feelings and romance, to feeling safe, understood, motivated and supported by the other person as a whole human being, enjoying sex for sure, but without alienating it from everything else.
I do not see how this person, sleeping with many women would be able to actually build a whole, mature and fulfilling relationship with any of them. it much more seems like he has been using women to satisfy himself while rationalizes or justifies his behavior.
It's not romantic nor respectful to start dating by talking about how many sexual partners you have been having and pushing you to get to bet as soon as possible. That is more than a red flag it is already a big fire happening in front of you.
Does it make sense?