Liking your stalker back can't be Stockholm Syndrome if they never even cornered you in the first place, let alone kidnapped or confined...
There is something slightly unhealthy about this relationship regardless (she isn't looking at reality quite straight, he likes her just because her expectations are of a normal human being instead of some sort of god/object), but on the other hand it seems likely that they will be able to negotiate their way to a happy and relatively sane relationship over time from here, if they wanted.