What is the problem? Mouth closed? Too much pressure? Mouth open? Mouth wet? One issue is that having you tell her means that she is probably tense when kissing you now.
You could ask her to play a game with you in which you each experience something sensually and then mimic what the other person does. You go first. Do not start with kissing her on the mouth. Kiss the place where her neck meets her shoulder. Then have her do that to you.
You get my drift. Work your way to kissing her on the mouth.
The rules are she can’t move while you pleasure her, and she has to mimic what you do to her exactly.
When she kisses you on the mouth, if it is better, praise her. Tell her that is just how you like to be kissed. Then ask her to show you how she likes being kissed (so this does not appear to be one-sided).