Havent been to the gym in 2 months, since that's when my kid was born.
Postpartum depression of some sort? Women can be kinda touchy after the birth of a kid, hormones are going nuts through their body, sexual tension, etc. It really sounds to me that this isn't about the bike commuting. It might be her. It might be something else in your relationship. Good luck. (Wife and I have had two kids. I learned the hard way with the first)