It sucks and it happens way more often than most would admit, get it sorted before having a kid cause that will be the end of your sex life for life... And also don't go fucking wg's to get back at her cause it will just make it worse
I found this book quite helpful after my first kid , good advice and common sense...
www.amazon.com/The-Married-Life-Primer-2011/dp/1460981731
Good site for people with this problem...
www.reddit.com/r/deadbedrooms