My boyfriend says he doesn't care if I were to sleep with other guys....?

I have been dating my current boyfriend for 7 months now. At the beginning of the relationship we had a long conversation on jealousy, and he expressed to me that he's never felt that emotion towards any of his previous girlfriends because he feels that it leads to irrational behavior and can consequently harm the relationship. I completely agreed with him on that part but he continued to say that he wouldn't even care if his exes slept with other people as long as it made them happy. When he first told me this I thought that it must have just been a way of protecting himself from his previously slutty girlfriends and unhealthy relationships by convincing himself "he didn't care". I thought that as time went by and our realtionship grew stronger, that he might feel differently towards me and maybe show some emotion when it came to feelings of jealousy. But he's repeatedly expressed to me that he doesn't care if i were to see other guys or even if I were to have ual relations with them because love has nothing to do with lust. I told him that his way of thinking concerned me because I'd certainly have a problem if he were to cheat on me and he ured me that he only wants my happiness and that he'd never do anything to hurt me. I just don't know what to think...I don't find it normal for a person not to care at all about their partner's relations with the opposite . I'm not saying for him to be a jealous nutjob but I just feel like his not caring about this kind of stuff is another way of saying that what's between us is not serious. I see it as human nature to be just a bit jealous because of the natural fear of losing someone you really care about...I don't know, is it just me?? What do you think?