To my way of thinking, relationships are about trust, including trusting one another's judgement. Of course, there will be times when your boyfriend feels anxious about something you are planning to do. That is normal. However, if he reacts to that anxiety by telling you you shouldn't do something rather than by expressing his anxiety and asking for reassurence or by talking through safety worries with you, then it's controlling behaviour and isn't ok. For it to be a healthy relationship, he needs to trust you to be loyal to him and also to judge whether a particular situation is safe for yourself. You don't have to go to every event your friends suggest of course, but it should be your decision, not a case of your boyfriend telling you what to do.
I've been with my partner a few years and often go to these sorts of events. We trust one another and check in through the evening, and we're clear about what we're both comfortable with and about what our insecurities are so that we can respect and reasure one another mutually.
Questions:
1. do you trust your boyfriend to be around other girls? If not, is it because you're naturally anxious or because you think he'd realistically break your trust, or both?
2. Do you want to be with someone who doesn't trust you enough to be around other guys?