Recently my girlfriend wrote to me:
This reminds me of the time before we were together.
Later she corrected herself:
This reminds me of the time before we are together.
Her logic being that we are still together. However, I feel like the latter is incorrect. Even though the more correct way of saying this is probably (as suggested by our American friend):
This reminds me of the time from before we were together.
– it is still confusing to her why the verb is "were" and not "are". And confusing to me, because I don't know the grammar rules behind these sentences.
How would you explain this to a couple of non-native English speakers?