Another option is meeting somewhere like Hawaii. Especially in the summer, there can be really good deals from Japan to Hawaii: have her check No. 1 Travel in Osaka.
As for you, the miles (in numbers, at least) would be much easier to get. You may also be able to find a cheap ticket for cash. The only other matter would be finding a place to stay; Hawaii does have good and decent hostels.
Of course, I understand why you would want to go to Japan!
Good luck!