Unfortunately, there have been so many individuals from her home country who have violated the provisions of their visa that legitimate visitors are often denied visas. The manner in which you immigrated could also be a red flag when she applies although your situation of a work visa should not be one of those. Also, mentioning a very long planned visit that is not as a US resident in similar circumstances could make can be an issue; for example, few US workers could take a 6 month leave from their job - 1 month perhaps but not 6.
When you write a cover letter to the consulate, point out that you realize that you could file for her green card and list the reasons you are not doing so. Is there a milestone event that you will be celebrating soon? In my family's experience, they obtained a visa for a wedding but not just a visit.
Before applying again, I suggest you consult an immigration attorney with experience dealing with individuals processing through that consulate to see what advice he/she can give you.

