Is marriage becoming obsolete due to cultural decline?

1) What kind of claim is this?

This is a social decline claim with a cultural cause.

2) What context is assumed or missing?

Marriage rates, definitions, and time frames are not specified.

3) What has to be true for this to work?

Cultural change would need to reduce marriage steadily and permanently.

4) When would this not hold?

The claim weakens if forms of partnership shift rather than disappear.

5) What follows if we accept it?

Marriage may be framed as fading rather than evolving.