Probably you're seeing the number because it is her favorite number. A number in mind seems to be noticed more frequently in the environment. See the environmental reminders article.

There are three major numbers in a numerology chart calculated from the letters of the name – heart's desire, destiny, and personality.

Her numerology heart's desire number and personality number are both 6. Your numerology destiny number is 6. The mirror-type resonance of the number 6 within the both of you is an indication that you got along very well together when you got along at all.

The numerological essence of the number 6 has to do with family, harmony, home, idealism, and healing.

The heart's desire number 6 tends to yearn for a harmonious home and other aspects of the 6 essence. Yet, because it is a heart's desire, the yearning will always be there – no matter how harmonious the home actually is or is not.

The destiny number 6 means its essence tends to be innate to the person's character. It may not always be expressed, and situations may not always reflect it, but it's always a constituent of the person's characteristics.

The personality number 6 means the essence of the number tends to be expressed to others.

The idealism aspect of the 6 can cause friction. Whatever the person's concept of ideal is can be expressed rather adamantly, or demandingly. Because it is seen as the obvious ideal, other people's concepts of ideal generally are seen as less important.

Now, let's talk about power numbers.

The numerology power number's influence generally gains force about mid-life. When the number is contrary to how they have been living life, it can be a reason for experiencing a mid-life crises.

Once in force, the power number's influence is present for the rest of the person's life.

Your power number is a 6, which is consistent with your destiny number.

Her power number is a 1, which is otherwise absent as a major number in her numerology chart. (It is, however, the same number as your heart's desire.)

The numerological essence of the number 1 has to do with self-determination, exploration, being alone, independence, and self-sufficiency.

It seems a bit early for her power number to gain influence, but by what you described, that may be the case. In that event, she would be feeling an impetus for independence, to explore new things, to be alone for a while, to make it on her own.

And finally, the numerology meaning of the number 616:

616 means hard or steady work building a solid foundation for the future in relation to home, harmony, and other aspects of the number 6.