Haha. Funny how football demands more time, loyalty and ties than any other sport. If someone never watched cricket for 30 years, or lost interest in it for 30 years, and then decided they were going to start going to LCCC, no one would think it was weird. Really it's a lot easier for the person whose dad tells them they're a Blue, buys the tickets and takes them along to everything than it is for the person who makes an active adult choice to follow a club. I'm guessing she's made a choice and it might last or it might wax and wane or fade like following a band and that's normal.
When I was a kid I decided I liked Miami Dolphins because I had an aunt who lived there and I liked the kit and the image. We didn't have our own NFL clubs. I grew out of it, but I might just as well have stuck with it. I don't see this as much different. The PL is the most interesting league in the world, the club tours the Far East to build support, and people pick a club fall in love with it, just like UK fans follow NBA, NFL, UFC. She likes Oasis, Oasis liked the Beatles, there wouldn't have been a Beatles if English kids weren't falling in love with black American R&B records - if something is special it crosses cultures. City is special.
What I don't think is positive is if loyal or local fans are losing out on tickets to resellers or being gouged and if a club loses touch with its city in the chase for half and halves. But if that happened it wouldn't be her fault - that lies with the club.