Being in a relationship with a spouse or partner who is constantly negative can easily develop into a daily living hell.
It can turn ugly very quickly, not to mention it also makes you feel unloved, unappreciated, disrespected, sad and lonely at times if not most of the time.
The only things keeping you there in the relationship is your love for the individual and the hope that things will become different some day.
You cannot stay in denial. You have to realize that there are two fundamental things to realize:
1. You cannot change your partner
2. Your partner needs to be willing to want to make an effort to make things better