Can’t we just be, what we want to be to a person, without naming the relationship? So if I feel like chatting everyday with somebody, I do that. If I feel like doing something for the other, I do that. If I feel like spending life with somebody, I do that. Do we really need to categorise them into some compartments, which we only created and which have only increased the confusion?
Let us look at the beginning of civilisation. Somebody would have felt that he is good person to chat with and I have good time with him. So they started spending time together, sharing their thoughts and doing things together (We call them friends).And then there is somebody, who feels like - I cannot live without this person. After meeting him/her, he/she becomes an essential part of the life. One feels a completeness with him/her. So they choose to stay together (We call it marriage)
But in these cases, reason comes first and then we name the relationship. Then only purity of relationship remains. What we normally do is, as soon as we meet a person, we try to fit him into a category in our life. So the relationship is named first, and then efforts are taken to adjust things as per that. It cannot sustain. There is such a vast degree of difference in our relationships, that we cannot put two people at same place in our life. They occupy a completely different space.
Take the case of marriage. In real sense, there is no need to do adjustments, sacrifices and so on. What I mean is, even if it looks like a sacrifice to others, it is not actually. So as Ashwita said, the spouse will learn to play the sport, it may look to others that spouse is adjusting or taking extra effort for maintaining marriage. But to him/her, it is gaining happiness from the happiness of life partner. It is so natural, if two people are in love.
But problem happens, when marriages are performed as a ritual, as a necessity. And then two people try to fit themselves into the expected framework. This may work out, but it will require adjustments and sacrifices and these do not sustain for long (at least these cannot let you have the real essence of love). Today there is so much hoopla and gyan on maintaining relationships, the reason is basic feeling is missing. People marry without having the right reason for it. Marriages happen first and then reasons are searched to stay together. That’s not marriage (or at least it was not meant like that, when it would have started).
I think the question is not whether best friend can be a good husband, but point is, anybody you are going to marry, is he the one with whom you want to spend your entire life? Is he the one who gives fulfillment to your life? Is he the one with whom you are yourself? Is he the one with whom your journey of life will be more joyful and enriching? Now, the ones we call as best friends may or may not fit as the part of life. It cannot be generalized. It depends on your way of life and values, and the way you define best friends.