Why did the Ancient Mariner tell the wedding guest about his voyage?
The mariner wanted others to learn from his lesson, he wanted to spread awareness perhaps, because he became a different person after he shot the Albatross and his color changed, his language and so on, and the Mariner chose a wedding perhaps he wanted random people to talk to, and he chose a daily event that is somehow circular, because the wedding is an element of life that will always happen regardless of the world around it. The guests at the wedding are merely people! And the wedding is an event that will happen even if there is war outside! weddings are everywhere and they happen all the time whether there is war or whatever… and he chose one guest out of the three which could be for many reasons and I think it might be because he wanted to show randomness or because he wanted someone who wasn’t an extremist to anything, like not too wise, not too sad. Or as I have said to be random to show that the Mariner just wants to spread his tale across the seas and all.