the jump into oblivion

I just dont understand how relationships work. Seriously is there a thin line between friendship and relationship?? and if so how do we know that we have crossed over.

Long ago I attempted to crossover this damn line but I ended up losing a dear friend and thus in limbo. With just a few words I had managed to lose her trust in me and ever since then we have never been able to be comfortable talking to each other. Now we are not even in touch...
It is like the very foundation of our friendship had been vaporized.

Ever since then I have been very careful with who I begin to have a deeper friendship.

Now my question is where does a relationship begin?? do people who fall in love start of from being friends. Is there a certain point in the friendship that they both understand that they should move into a stronger relationship??

I do have to ponder about this because in the next 2 years I will not be able to prevent my dear parents from pushing me into an arranged marriage: not that I am against an arranged marriage but it would be great to marry a girl I already love than marry a girl and THEN love her.

I have always pushed off the thoughts about relationships by thinking that I have other things, like job search, MBA studies and then again full time job search etc, which take higher precedence over the quest for love. But eventually I will have to fess up to this.... I lost one friend and am not ready to lose anymore.

I know it sounds silly but I felt going thru life without a dear friend is really disturbing for a single child like me. That one experience was enough to scare me.