Is it normal ?

Is it normal when you'r in a relationship and whenever your girlfriend / boyfriend talks to the opposite sex you tend to get a bit over protective?

I've been dating this guy for over four months now and every time he starts to talk to other girls that arnt tied down to a guy I get really uncomfortable but I dont know how to deal with it, besides that he's already had sex before and that makes me feel a bit uncomfortable + I dodnt even find out from him two girls I barely even know told me

I dont wanna lose him I cant go through another heart ache like before, he makes all that seem as if it's never happened. Maybe Im going over my head but I dont know there is just something about him that catches my eye every time.

Im mainly looking for advice please anything that could help me it greatly appreciated

why is it in our world we'r pushing youth into deciding what they want to do with thier lives? Sure everyone dreams about what they'll be like when they grow up but as the last years of highschool come froth into the iris of the present day everyone is running around trying ti figure out what we want to do with our lives how are we suppost to know at 16/17 what we want to do for the rest of our lives and practically every job out there now requires some post secondart school training putting students into thousands of dollars into student loans and such then theres trying to find a way to pay for all the courses you take while at school so you need a job and so on and so forth
why are we pushing our youth into deciding what they want to do with the rest of thier lives