I loved the last two lines of this poem so much. I just feel like they brilliantly encompassed everything you wanted to say here about moments and how quickly they pass and how beautiful those privileged moments when someone else allows you to see their vulnerability is. I feel like, as far as constructive criticism goes, really playing with the line breaks as a way to switch up the pacing of the piece would really work well. For example:

Remember when I promised you
forever?

Well I only meant tonight and
the little bit of air left in the high
of my lungs. So keep me alive with
the onslaught of your breath, the wet
corners of your lips pressed clumsily
against my own. Let us draw this out

etc. Asyndeton is great for speeding up works, etc. But the last two lines - and really all of this poem - are gorgeous.