The lets just - be - friends line is usually used to soften the blow. He is either a coward and doesn't really mean it (but would never admit as such to you) or he is really quite selfish and wants the priviliedge of having you around but on his terms entirely, albiet in a non-commited capacity.
If he liked it, he shoulda put a ring on it and then kept the ring there.
I am acknowledging your magnificence.