The “Boys think with the wrong head” thing real?

Hi! I’m a 18 year old and my boyfriends 17. He was a pretty late bloomer in the sense that a lot of people around him and his friends were having sex and he hadn’t even made out with anyone at the time. So, when we got together I took his virginity. we’ve been together about 11 months now and I guess I’m wondering … would someone (especially a boy) not be thinking about having sex with other girls and exploring ? Because I know when I lost my virginity I was curious. Will he leave me to explore with other people or am I just being paranoid?