what are friendships?!

What are they, really? The moment to just celebrate a birthday? or to celebrate their wedding? or to really maintain them throughout our lives? Do our personal lives really drive us away from those people we met in the past? Being work, school, or whatever we are doing. Can we really put other things before friendship, other than family nothing is more important than family...

How much does it takes to just say "Hey how's it going?, what are you up to?, how are so an so?" I for one think it doesn't take much to just ask what are people up to, but at the same time I think others do think it takes too much. Up to some point I try to not keep in touch with some people, but my personal feelings and the way I just am don't let me do that. I like to keep in touch with my friends, hell I keep in touch with them more than my family. But I like to think and I think that my friends are my family!

Will finish with one request, this happened last night, it was my ex's birthday and no I did not forget. I mean could anyone really forget a birthday of someone they loved for 6 years? Could such a thing be possible even if something horrible happened between both, could such a thing really happen? This is what she wrote to me for the first time in what it's like 6 month,

11:21 PM Ex's-name: al parecer ya se te olvido mi cumpleaños
11:22 PM espero estes muy bien
saludos

How would you go about this?

Edit: Forgot to translate the quote above, "it seems that you have forgotten my birthday, hope you're doing good, greeting"