Boyfriend traveling without me??

My boyfriend and I have been together for quite some time and things are serious between us two...so I very shocked to find out he’s planning an international trip to travel around Asia in April and is going with his cousin??? Mind you it was a problem for him that I went on a 3 day trip to New York with my parents back in November...and he’s planning on being gone for a while and didn’t even think of bringing me along or even offering?? I don’t know if I’m being weird about this or what but I feel kinda crappy about this and am not sure what to do or if I’m totally over reacting to this.