I’m not big on jealousy. It should be okay for either of you to be friendly with the opposite sex. Even light flirting can be okay if it just in fun and goes no further than that. If you don’t have trust in a relationship then it is bound to fail. My advice is to put your relationship to the test and allow flirting on both sides. If that causes the end of it then it wasn’t meant to be in the first place.