Why you ignore it
You want to be the “cool” girlfriend so you just tell yourself, “I’m not his boss! He’s a grown man! Good for him that he’s traveling for three months…! He can go find himself and learn new things…!” Oh please. Because you won’t admit it to yourself I’ll say it for you: a man should want to bring you on that trip for three months or at the very, very least, want to discuss it with you to make sure he wouldn’t be missing any big events in your life, or to give you the option to say, “I’ll miss you so much! Can’t you just make it two months?” And he should want your opinion on the apartment he’s moving into if he plans on you spending tons of time there! It’s not too much for you to ask to be included in these decisions.