Some men are creeps like that, and you just have to tell the kid that Daddy made another choice.
My X called our son the week before his 4th bday to wish him HB and let him know he couldn't come to be with him, he couldn't afford it (from Hong Kong to DC). In the same phone call, he said he was flying to Vietnam next week to pick up his girlfriend, then flying them to New Zealand (his home country) to get married. DS4 picked that up, hung up, cried to me and asked how daddy could afford to get married in NZ but not come for his bday. I was stumped, but decided to say that everyone makes choices. Sometimes they're wrong, sometimes they're right; sometimes someone thinks that they're wrong--it's a matter of outlook. So we did extra-special stuff for his bday that we wouldn't have done if X had been here.
DS is 13 now, and X STILL finds reasons not to visit, though he's in Vancouver, Canada, now. Still a jerk, still flying the world, but can't visit his own son on the other side of the continent. He was here for two weeks in November last year, doing PhD work at a local university, staying in uni housing. He saw DS12 for about five hours, stalling until he heard from Ohio friends whether they could visit them in Ohio. By the time he heard NO, then he wanted to get together with DS, but by then he had only a few hours until he had to back at the uni. And the uni wouldn't allow overnight visitors, so staying with X was out of the question. He did manage to rent a car and see DS's stage combat performance, but not after complaining to DS about how expensive it was to rent a car in DC.
Some people are a waste of good organs and air. Try, try, try not to let it bug you. Vent to friends like crazy. Tell DS that daddy made other plans. She will draw her own conclusions. DS13 now thinks his dad's a greedy, self-centered man. No points for guessing the two top reasons I left him! ;-)