I would probably try to narrow the topic down a little. "Marriage from medieval to Reformation Europe" or "marriage in Jewish tradition" or "marriage and feminism" or "wedding ceremonies" or some such. You could also think about whether you want to go with a normative investigation (what theologians, priests, etc write about marriage; ideal marriages; ideal roles in marriages) or descriptive (how actual marriages function on the ground). That will go a long way towards helping you find some good books to start with. It might also help AskHistorians readers help you find some useful ones. ;)

Generally when you have a topic like that, you can search your library catalogue for the most recent book on the subject you can find, and then comb its bibliography for things that look promising and interesting. You can also run an Internet search for "[topic] bibliography" and "[topic] literature review."

Unfortunately, a lot of search result space is now taken up by Oxford Bibliographies which are paywalled, but you can get to good stuff if it's out there with some patience.