[sliverstorm]

We can only read so much into that statement.

Did she say "I must have a diamond that costs a minimum of $15k, or else I'm leaving you"?

Or does she get kind of sad & blue & disengaged when he pitches alternatives, because she dreamed of a diamond ring as a kid?

The later is quite understandable. Even if you think diamonds are silly, it's a matter of fact women in the USA grow up surrounded by diamond culture.