this is what i think, I think the reason why people turn to poetry to express the pain and pleasure of love is for them to make memories of how their relationship was and felt. I think they also write poems because sometimes it feels good to get things out for example; some people write to express how they feel, some people talk to others to get things they had in their chest out, some people like to break things, and some people like to write poems and songs. I don't know if this helped but i hope it did