A wedding should be one of the happiest days of a couple’s life, but for some, it can be all too revealing of trouble to come.

How a couple reacts on such a high-stakes, often-expensive day can be a warning that you may have married the wrong person.

Take it from wedding photographers who are documenting couples’ interactions in real-time. They’ve seen it all. “You can definitely tell when a couple is in love, there’s so much chemistry,” said Chicago-based wedding photographer Rocio Pagoada. “It’s so genuine in the pictures.“

However, some couples don’t seem as happy to be with each other.

“I think seven out of 10 weddings are great. And then there’s the random few that are like, ‘OK, why are they getting married?’” Pagoada said.