Evolution at its' finest. You're not lucky; it's just simple biology. The two of you weren't made for each other, and if you ever split up, the next person you meet will be even greater than the current. Why? Because you are simply fulfilling a biological need. Enjoy that oxytocin-fueled dopamine rush, my man. That's all that love is anyway. Once the oxytocin quits firing your cylinders, the sparks and butterflies magically go away. We all wish we could fire it back up with again, but alas, tis gone unless you find a new person.