Bear with me, here.

Human thought is transient. Never forget this. If you can't place or grasp the present (and you can't, because the present moment only exists in that ever-changing, constantly-shifting divide between the moment before it and the moment after it), then how can you ever hold a thought, feeling or perception eternally?

Human thought is fragile and fickle, and easily punished by itself: it's quite easy to convince yourself anything, or talk yourself into believing anything. Statements like "I will always love you" and "Always and forever" are very romantic, but romanticism is an ideal; we live in fear of the moment, and naturalise ourselves into feelings of "ever after" (think of fairytales taught to kids).

It's a cynical outlook to some but for me it's the key to one's own self-understanding and happiness. It doesn't mean you can't love, or desire or lust after someone. Those are all natural instincts and you'd be a sucker (or religious) to suppress them; but alongside that, don't fool yourself it'll last forever and ever. It may, but that's merely coincidence. I don't believe in fate.

So: yeah, you'll get over this. Time heals stuff without us having to be aware of it; rebounds help, too, as long as you're honest about them (and with yourself: again, it's not going to last). To expect too much from things is to live in hope; and hope is constructed cushion: to have hope is to acknowledge its necessity - it's a veneer upon reality.

Sayings like "it wasn't meant to be" are silly but true in allegory:

If your girl was the greatest girl in the world (to you, to your subjective individual world) you'd be with her still. If she isn't or wasn't, then there's little point in being with her; too many people stay together out of fear of spending time within their own minds. Re: fucking other guys, there's nothing stopping you from fucking other girls.

And the fact it's even about "fucking" is telling. Bodies are bodies; flesh is flesh. Technique in bed differs from person to person, I'll agree, but it's not all that important. Physicality binds people in the first place because we all have it; it's not unique to your girl.

As for emotional and intellectual connections; it's these that grind the brain most. Memory's vulgar, but returning to something is also a vulgarity. Living "in the past" puts tremendous pressure on the future; the key is to be at one with your current state of being. Basic breathing excersises help with this; walking long distances, too. The clarity of vision at dawn is profound indeed.

Don't hide from the fact you're feeling hurt; don't hide from the fact that it'll pass. Don't be afraid to "let it out". We're all human; we're all concepts of flesh limited by thought.

Don't limit yourself by thought.