I think, at least some of us, fall in love instantly without even knowing it. And the time between then and the point where we actually admit it to ourselves, is more about acceptance, either social or personal, of how long it should take to "get there".
How else would you explain that once you know you're in love with someone its almost impossible to remember a time when you weren't in love with them.
The downside of this theory is that should things not work out, its so ******* ******* hard to get back to a time before, a time when you weren't in love with them.
And maybe we never do. Maybe we never fully recover.
Initially it's the immediate changes that carry the most pain. No morning greetings on your phone, no shared nonsense during the day, the kind of nonsense only couples share, the empty bed... the feeling of once again being alone.
In time though those moments get forgotten, or at least replaced by new routines that help avoid them until enough of the pieces are back together that they don't hurt anymore. You no longer have to fight the urge to say good morning the moment you wake up; going for coffee no longer feels like an inside joke you have to share; going to sleep is no longer something that follows a two hour phone call.
But the bigger stuff, the truly great memories, they never go away. We find ourselves looking back on them with fondness, for comfort, proof that it did happen, that we were once that happy, that for a while at least we felt like we had it all. And sometimes we'll know why it ended and sometimes we wont; and as frustrating as either of these scenarios are, we'll accept that it doesn't really matter.
As long as we get to keep those moments.
It's those moments that make me question whether or not we ever truly stop loving someone. No matter how hurt we feel, no matter how much we feel they hurt us, deep down, if we're honest, we all have those moments, even for those who hurt us most. Sure they could be hidden behind bitterness, buried under blame, locked up behind the walls we let ourselves build as some kind of protection, but they're still there.
You're all still there.