When you don’t have sex within a year, that’s sexless marriage and when you have sex less than 10 times yearly, it’s a low-sex marriage. Sex once a month implies 12 times a year… so it’s definitely not a sexless marriage. However, if your libido is much higher, your definition of a sexless marriage might be different. If you feel it’s an issue, you can’t bond with your partner properly emotionally or sexually, then communicate with your partner.