Guys: what do u think..My boyfriend will take a vacation to Europe w/out me...I feel disappointed & upset?

Together for 3 years.

We are in our 30's.

He works at an adult language school where his title is an activity coordinator. basically he takes students out to many activities. He gets to know them after activities as many of them want him to hang out with them. The students are young adults (18-26) from various parts of the world, especially Switzerland (that's where he is going) and come to the US to learn English for 1 to 12 months.

Im sad b/c not only did he not ask me whether i want to go with him but because I feel jealous that he will be seeing people (especially girls) I do not want him to see again (although he keeps in touch with them on facebook). I never met them. I did talk to him and he says its one trip before settling down with me (if we get married).

I contemplated breaking it off with him b/c I do not want to be jealous. He was sad when I mentioned the breakup and gives me space to think. He also stated that if I am jealous because he has friends that are girls, then we should break up. He is right, I am jealous that he has friends that are girls. This is not about cheating. I need to make more friends that are boys...I guess.

Should I feel this way? AM I WAY too insecure?