Yeah, I can see you care about this girl, but perhaps you need to explore the idea of relationships a bit more.
I mean, it might sound harsh, but nobody owes anybody else an explanation as to why they don't feel the same as they did, or realised they weren't ready to commit to something - or any number of reasons, despite how painful that may be for you.
It's just the way it goes, I'm afraid.
In a perfect world, relationships would end with a gentle but honest list of reasons why your love is not reciprocated.
But can you think of any part of human relations where this happens? Maybe in a really well managed workplace, but very rarely (unless the reasons are obvious, such as incompetence, poor behaviour etc).
But even if you find someone you love, or could love (which some find difficult enough) you then must contend with the other person's complicated emotional/interpersonal/plethora of other needs.
The chips are stacked against all of us in this sense - but that doesn't mean it's impossible to find the relationship you are looking for.
Unfortunately there are very few clear indications as to which relationship could be one that fulfils and brings both of you happiness.
If this isn't it, you need to stop torturing yourself; not only will it eat you up inside now, but it will most likely affect your future romantic or sexual entanglements if you get too hung up on this one.
Hard as it may be, if she is not reciprocating, your feelings will pass.
Think back to your early crushes, adolescent heartbreaks (I don't know how old you are, so I'm simply presuming here that such things are behind you...) - the sting has gone out of some of these feelings over the years, right?
I think it is important to realise if something isn't going to work (even - especially - if it is contrary to your emotional 'instincts') because pining for someone that you've had fun with - but has maybe moved on (or whatever) - isn't going to do you or the situation any good.
A lot of my male friends have close, platonic female friends who started out as a crush or a fling; sometimes chemistry just isn't always relationship material, but the budding of a friendship.
Either way, I think you need to think about your own emotional wellbeing here.
Realising that maybe things won't work as you hoped or expected is not 'giving up' - it's having the respect for both parties to just to be realistic about what's going on.
Getting blocked on Facebook and stuff is a pretty clear indication in my books (and others, i assume) that it's time to back off, give her some space.
There is nothing like travel to put life into perspective. Regardless of what her "real reasons" are (assuming there are any - and it's not just some interpersonal/emotional/freedom thing) I think the more you pursue it the less likely she's going to be the one to give you the things you are looking for in a relationship.
Sorry man, I think you need to just put yourself out there and meet new people. Hanging onto this hope is only going to cause you pain, from my reading of it anyway.
