A relationship really DOES take nurturing and time. It's extremely hard to keep things going if you rarely see each other and talk. Closeness requires verbal intimacy, knowing what the beloved is up to everyday, caring about the minutiae of his/her life and sharing it...developing that trust.
Sure, it's easy to be attracted to someone and may have that attraction to him/her all your life, but true intimacy is harder than just that familiar bolt-of-lightening feeling.