One day the glass will be broken, if you compare it to a glass. If you compare it to a pen, later it will be like throwing a refill after ink gets over.
If you compare it to a ship, it may sink in water, if you accidentally compare to a sea after some time it may have a tsunami attack soon.
If you compare it to eyes ,closing of eyes may take place sooner. By comparing it to moon we can think we are becoming poet, but it’s a great illusion because sooner the new moon day may arrive and there is total darkness in the sky.
If you compare it to rain water, it may percolate sooner into mud. The flower may get dried ,if you compare the precious friendship with flowers. The poem may have an end, if you dare to compare it with a poem. It may be a foolishness if you tell friendship is like an iron, iron may get rusted soon. The pearl may loose shine, if you try for metaphor the friendship with pearl.
Stop comparing, the friendship the holy which don’t have its simile, its metaphor, no personification, Friendship is endless, which will not lose, which doesn’t stop, which will not rust, which will not crushed. The friendship the understanding, its respecting each others feelings, sharing each others happiness and each others sorrows. Instead of searching for the aliter of the word friendship its better to feel friendship is the simile of itself, it’s the metaphor of itself.