Can you possibly list a few examples of things you could do for her? I mean her just vaguely saying you need to do more but then saying she can’t tell you what isn’t very helpful. So maybe try offering a few things and seeing if anything strikes a cord:

Do you want me to plan more of our daily activities? Do you want me to help more around the house (if you live together) Do you want me to touch you/cuddle you/whatever more?

See where this conversation gets you.