A few answers:
-the girlfriend is a millennial.. 10yrs his junior.
-They've been dating 3yrs, only met the family once.
-She works part time. Her family cut support, which my brother apparently took over.
-Older brother's wife and two kids all got 1st class tickets.
-We promised Grandma that we'd all be there for her 100th Birthday. It's a big deal.
He's talking about getting married someday; given the circumstances (and history), we'll probably cut financial support as well.
The way things are going, it looks like he's forcing our mother to get her a ticket.