Out this month

Denise
AF showed up today, not sure what we are doing wrong, I never had a problem before!!! I have 3 amazing kids and can't seem to get preggo with my fiancé, I'm starting to wonder if it's him?!? 
I'm on a regular 27 day cycle and AF is never late, always on time!! 
How should I bring this up to my fiancé. Should I ask him to get checked out? He is the one who wanted to try  for our first, his first, baby! I was very excited but now feel emotionally drained and feeling hopeless. Thanks for listening and allowing me to vent, 😔
Baby dust to all!!!