Question

Why might somebody give you a tearful goodbye?

because you have plans to see each other again
tomorrow
because you won't see each other again for a long
time
COME

Answer 1

Because you won't see each other again for a long time.

Explanation:

Because tears convey emotion, typically sadness, it would be safe to assume that they won't see each other for a while, because this would provoke an emotion of sadness.