A blog idea on relationships, love and marriage can contain timeless topics that people are always interested in. Have you considered the idea of blogging about reviews and experiences of real people?
People are more likely to engage with content as they can relate to it. So, indirectly, you would be creating a sense of community by blogging about love and marriage reviews.
You might have noticed, this is a very focused topic and you can target a niche audience. There is scope for monetization if your blog becomes popular. You can employ the usual methods: advertising, affiliate marketing and/or offering your own products or services.
However, do maintain high ethical standards as the topic is very personal and sensitive.
Suggested blog name: LoveMarriageReviews.com