I would compare friendship to building a fire between two people. The stronger the friendship, the greater the flame. But all fires need fuel - if it is not fed, it will eventually subside and grow cold. Likewise, if two people do not keep in contact with each other, their friendship will fade.
How do you start a fire? The moment a stranger greets another, a spark flies. Over time, producing enough sparks will set off a flame with a steady glow. Such a fire is easily kept alive when the two have a close proximity to the flame. Once the distance grows, keeping the fire going requires more effort.
As with multiple friendships, each of us will have multiple fires to feed. Running between these fires uses energy. Given that every person has their limits, not every flame will be able to be fed. As such, the other party would have to take a turn at fanning the flame to keep it burning. If neither is able to keep it up, then they become strangers again.
With this in mind, striking a match when there is no base for the spark to live on would be wasted effort. At the opposite end of the spectrum, it would not be a waste to ignite a crate of fireworks doused with petrol on top of a volcano to save a friend from making irreversible adverse decisions.
So, I've got a box of sparklers, anyone wanna play?
