So often I've read on mn mothers saying they barely have sex since they had children since they are always tired or don't feel like it. But really, how much effort does it take once or twice a week? You need to work on relationships, and sex is an important part of it. And the more often you do it, the more often you feel in the mood.
If you don't have sex with your husband, it'll be no shock if he finds someone else who will.