what we're having - filling the gaps and planning the structure

I think I'll make the intertwined part were 'she' and 'he' are singing alternately the prechorus. It now reads:

He:     whatever happens
She:    I could not stand it
He:      I must not lose her
She:    if it ended
He:      whatever happens
She:    with full zest
He:     I will be true
She:   I'll give my best

I checked my Rhyming dictionary for words that would rhyme with "best". The lines first read:

our love is blessed
I'll give my best

But I don't care much for blessings ;-) There's enough schmaltz in it already without religious connotations.

I also refined the chorus:

what we're having
is so special [or precious - I'm not sure which to prefer]
what we're having
can't be explained [replacing "quite unexplained"]
what we're having
is pure magic [instead of "is like magic"]
what we're having
must be retained

Next I will write two verses, one for him, one for her. I'm imagining a structure like:

verse (he or she)

verse (she - the other one)

prechorus (see above)

chorus

verse (either each singing half of it or both singing)

prechorus

chorus

[instrumental interlude or bridge, I'd prefer an instrumental part because the text, as it stands at this time, doesn't seem to leave too much room for adding another perspective]

chorus