I've never ever had a "breakup" with a friend. Generally speaking the friendships of my past died without any conflict. The most common reasons are our interests changed, one or both peope relocated, serious relationships/marriage or family take up more time. Some friends are with us for a season and others are with us for life.
Having said that I suspect women rely on their friends more for "emotional support" than men. Guys tend to rely on their girlfriends/wives for emotional support. I have not seen my two best friends in 5 years and haven't spoken to them all that much via phone or email since I moved from California to Chicago. However I not only still consider us to be best friends but brothers with different mothers! Speaking of which I haven't actually seen my own brothers in almost 6 years and yet they remain my brothers!
Friendships are a state of mind.
I believe "friendship breakups" are more common among women especially those under the age of 40. Younger people to get into each other's "personal lives" in such way that it leads to "drama". The older one becomes the more (selective) they are about what they share. A true friend wants you to be happy and vice versa.
"Friends are the family we choose."
One man's opinion! :-)