Crossroads?

Few days ago, I had a very strong need to write about love and friendship from the point of view when a person is at the crossroads where the only possible way out is to choose between two options: to keep friends and lose lover or to keep lover and be prepared to lose friends... I couldn't do it properly because I just tried one of the options in practice when I was in my early twenties. So, I wasn't able to completely understand the problem or, put it this way, a need to make a choice. Recently, I was forced to think again about it.

I guess everyone tried one of the two options mentioned above in practice, and there is not insignificant number of those who tried to experiment with both. But as people become more mature, it becomes obvious that things are not always simple, and that there is no need to cut off anybody, neither lover nor friends. At least, I used to think that way but I'm not sure anymore because I missed to notice that one more option existed as well.

What I did have recently was experience which actually made me think about the matter one more time because that other, missed option kicked me right in the face. Being in a serious relationship myself (at least, I thought it was serious), I experienced that feeling of being buried alive because a very large number of my friends just forgot about my existence at the very moment I moved to my ex-boyfriend's apartment. That type of rejection was really new to me, it was like making a step into the unknown and that 'unknown' left me with the really big question mark hanging above my head. I understand that my friends must have based their opinions on some kind of prejudice but I still don't have a clue...

Why it is so hard to make things work in a way which allows someone to keep both - their lover and their friends? If things are not black and white and people do grow up at some time of their life, why do they still behave like teenagers and in their late thirties or forties still show high level of immaturity by presuming that their friends made a choice between love and friendship? Why are people still ready to make 'decisions' instead of others and behave according to that imagined decisions?