Why is this happening? Why do some couples live together all their lives, while others are not able to stand the test of everyday life time? For my In my mind the reason is simple. Love is a concept that is difficult to interpret. For each person this word It means something different to each of us. Personally, for me, To me, is its a combination of passion, the desire to support each other, and the desire to share the joy for two sharing in eachother's joy, mutual respect, and so on. Feeling that prevails over the people in the early stages of relations is a Passion is the first overwhelming emotion, causing That's why people in love can to act compulsively. commit so many rash acts. The initial phase That passion carries with it brings a lot of many emotions, feelings, and impressions. thoughts, but this period can not it doesn't last long. forever. 

Over time, the this passionate relationship to each other between the two lovers must go to the next stage evolve. It seems to me that the relationship should be more closely related grows deeper. Despite the fact that over the years, passion may subside subsiding after a few years, to be it is replaced by stronger feelings come, greater emotions, such as like respect, gratitude, affection, admiration, common interests and unity. In addition to all, people have something All of these emotions share the common bond of the couple's history, memories, and mutual achievements.  togetherare that connects them: their history, memorable moments, and the achievements that they have achieved together.
In my opinion, the feelings that people get after years of living together - is the real strong feeling called love. Over time, True Love is made of all these things. Older people will tell you: 
True love comes with age. That is why the first bright flash of passion doesn’t always live to true love.