They say a true friend is when you can sit together in silence and not feel awkward at all.
(Note: trough is the highest point and crest is the lowest point.)

Then the relationship normally disintegrate and moves on to the crest or just die off all together. Why? Most common reasons are time, like going on for so long without meeting the person again. Or no common interest. Conversation just die, see? Or maybe even bad impression on the 1st Encounter.
Then if the relationship survive again, the closeness level increases to even a greater magnitude. This is due to when we continue to meet up with the person, and basically share common beliefs and interests. Then slowly, a bond of trust is formed. Then at the top of the 2nd crest, we have already established the fact that you and the person are normal friends. You don't really feel completely awkward or elusive around the person.
What I meant when I say you discover something totally alien is when the relationship really gets personal. REALLY. You start to find out all the things about the person on the personal level. How do I say this? Like you find that the person hates it when you smack their back. Or the type of character that they have that you don't like or vice versa. Or like either of you have an inferiority perspective of each other (Like he/she is greater than you in studies, carreers or popularity). Or like you feel that friend has ditched you to hang out with cooler people.
Backstabbing, you know whats it like, so enought being said.
The possibility of bringing the relationship back is extremely low. The factors that helps bring the relationship back are mainly revolves around you. Will you actually find the guts to forgive them? Or will you have the valor to continuosly love the person unconditionally? This is what a true friend is.
The thing that makes the level of closeness ever escalating is when the relationship becomes mutual. Both share to each other the thoughts and give and take criticism. Both working together for any purpose. Both helping each other in time of need or even when there is no need. That is called being a nuisance but those who are being a nuisance normally cares a lot for you. (Or because they are jealous)
In the end, a relationship that survive all the toils and tribulation is a relationship that is definitely worth fighting for.
I am not a professor but just a 17 year old kid who based this theory on experience. But it is a theory nevertheless. A theory remains a theory in the end unless proven with sufficient evidence. Then it becomes a law.
I hope this doesn't bore you to death and wouldn't blame you if you discontinue reading halfway through. If you read it all the way to the end, then congratulation to you for understanding what goes on in my head a little better.