Lovely :O)

"That what we have is up for keeps"
I think you could use another word to start this line, having that and what side by side is a bit confusing.

"Wondering how I had the good fortune
To find something so incredibly rare"

I love those lines! They were the perfect metaphor and image.

"Sometimes when we're lay together"
That line should be either'
'Sometimes when we lay together'
or 'Sometimes when we're lying together'

"Already know want us to last forever"
The last line didn't make much sense.
I think you're just missing an 'I' between know and want.

Overall it was a good poem. You just need to fix the few mistakes and it will be good. Again, I really like the rhymes you had and the flow was good.

Keep it up!