Whoa! "I am considering buying a ticket and surprising him. Bad idea?"

That right there? That shows these two people are not in the same place at all. She's ready to stalk him to other countries. He's so uncommitted, he's willing to hurt her feelings to travel internationally to party without her. He had to know it would hurt to be excluded, but he chose fun.  

Who does that? Somebody who's just not that into the person they're dating. Some guys choose women that they aren't "really into" on purpose, it gives them all the power. (Yes, women do it, too.) If she's looking for the real thing, she hasn't found it with him, IMO.