I'll give her the perfect life and she'll never want for nothing.
I really, really feel for you. Honestly.
OK, just a few things:
You know that 'honeymoon period' and all that stuff where everything is fluffy and sweet and romantic? Sadly, given our chemical make-up, it simply doesn't last forever. It can re-occur I gather, as you hear about old couples 'falling in love all over again'. Apparently it lasts on average between 18 months and 3 years, depending on the person.
I think that when you're still young, when there are no ties like babies, mortgages, marriages etc., AND neither side has really had much experience - when said honeymoon hormones start to wear off, there isn't much solid stuff to keep it together. Rearing a child and making a home together brings up other hormones which form an attachment, something more long-term.
Finally, hormones and chemicals aside - to last despite all of these things - there needs to be real admiration and understanding and connection between two people. You might have got it together cos you liked each other a lot but you know, there may be someone out there who fits with you better!
Another thing I forgot to mention is that her mate recently split up with her boyfriend and they started a few weeks after us.
I remember breaking up with my first long-term boyfriend, who I started seeing when I was 17, him 19. We lasted 3 years, though it really should only have been two. I had started to fall out of love and get a bit depressed about it, but because I didn't want to throw away what we had, I tried really really hard to get 'the feeling' back. For a whole year.
The trigger for me eventually biting the bullet and just saying "I just don't think I will be in love with you again" came when two of my best friends (who'd been together 4 years at the time, I think) broke up. It wasn't like I wanted to be free and single because she was - far from it - it was just that suddenly I saw I didn't have to feel miserable and guilty all the time.
That's what I felt, REALLY guilty, because I couldn't give him back the love he gave me. I tried.
She probably does care, a lot. Otherwise she'd just have disappeared with a lot less fanfare.
Basically, she's fallen out of love - she probably wishes she hadn't, as she realises how much you two have together - and simply can't go on pretending like it's all OK. She's just as unable to fall in love with you again as you are unable to persuade her. It's happened to me twice and both times it made me so sad, so numb, and SO guilty.
Currently I keep going nuts over my new boyfriend because he's ten times the man either of the other two ever were, and I'm SO scared of the same thing happening. I don't want to fall out of it this time. I'm scared.