Hello from JustAnswer.
The usual approach to this type of issue would be to seek counseling as a couple. However, as with any counseling, it would typically involve her wanting to address the issue, so she would need to want to participate and seek resolution to the issue.
There also should be some consideration as to whether there is a specific medical problem that is contributing to this, such as pain in the vagina that is worse with intercourse. From this perspective, an evaluation by her OBGyn would be an appropriate step.
If I can provide any additional information, please let me know.