[23/F] My boyfriend [23/M] doesn't know how to have a conversation.

My boyfriend [M/23] and I [M/23] have been together for two years. He is a big talker while I do not talk a lot. This works really well for us during one-on-one time because he likes to talk and I like to listen. However, whenever we spend time with friends or attend social events he tends to dominate most conversations. Also, the only way he seems to know how to talk to someone else is to relate the other person's comments to stories in his life. AND he tends to get caught up in insignificant details while telling those stories ("On Monday, was it Monday? Tuesday? No, Monday. It was definitely Monday"). People start to get that glazed-over look. He really has no idea how one-sided these conversations can be. Should I talk to him tactfully about this? Should I accept it as quirk and let him talk?

TL;DR: Boyfriend tends to dominate conversations with other people. Should I say something or let him be?