Notice the positives in your spouse. Notice abilities, talents, efforts. Name them. State examples of where you have seen them.
“You come up with such innovative solutions, like the time when …”
“You make me smile when I’m feeling stressed. For example, just now when I …” These fuller statements help the other person feel seen and appreciated. So much more than a simple “I love you.” or “You are so good.” As a bonus, these kinds of things are circular in that the more you notice and acknowledge them, the more the other feels valued and will do more it.
And don’t forget to notice and acknowledge your own positives.