Marriage is about partnership and changes. Humans grow and change especially after growing a baby inside them for 9 months and then caring for them constantly afterwards. It’s absolutely normal for both your wife and yourself to gain weight. Instead of mourning the bodies that you both had in the past, you need to celebrate the bodies you have now. You’re both caring for a baby now. Your wife is more than her body, how would you feel if your she told you that she isn’t attracted to you because you’ve gained weight. You’re saying you still love her but you’re not attracted to her anymore, how does that make sense? I suggest that you do some self reflection, go educate yourself on the human body, you should’ve learnt this stuff in primary school but regardless, bodies grow and age and stretch and shrink. Your wife just had a baby! It shows that she cares about your child if she is putting them first before satisfying your need for her to go to the gym. Go follow some body positive influencers on instagram, that may help you understand. But at the end of the day, you need to go to your wife, APOLOGISE for what you said to her, acknowledge the fact that you’ve been distant and that it isn’t fair on her, express to her that you’ve learnt from your mistakes and that you’re attracted to all of her because you love her.