Sigh...
To talk about love is very troublesome.
Does love have the sweet side only?
We need to be very honest to ourselves, face our emptiness our loneliness and have courage to face true love. If your friend think what's between them is true love.
Find some happy love instead of time- proof-love.
Relationship doesn't disappear or go on itself.
Be courageous to say good bye or go further.
Otherwise there will sum up too many secrets between family members because of this affair--no matter pure or sex involved. It will become disaster soon.