Second, looking through the binary lens of 'creation' or 'destruction' is reductive. Plenty of anthropological, sociological and historical evidence seem to suggest that as a species we are capable of being organized in many different arrangements. I acknowledge that marriage 'feels' like a more straightforward institution to enforce with clear benefits to individuals, but I would suggest that you strongly consider that it too has sharp limitations, including aspects of oppression or suppression (e.g. for the more naturally promiscuous) historically.
In general while the assertions and influence of the postmodern project are a mixed bag. They've led to overt widespread cynicism and loss of meaning for many in our time, but they've also brought with them an invaluable tearing down of assumptions that would otherwise be treated as unquestioned narratives of reality. [2] I would hope that awareness of such realities won't lead us down disarray but to an embrace of the fact that there is great diversity in the way we live, and that fixed constructs such as marriage might no longer be capable of solely accommodating that, but might instead co-exist among other arrangements and notions that can.
Thirdly, I would suggest looking into 'metamodernism' which we seem to be slowly beginning to enter. One description you might consistently hear of it is that it's described as if it's an "oscillation" between aspects of modernism and postmodernism. - In other words, an answer to postmodernism's shortcomings and negative effects, while still not abandoning its realizations. [3] [4]
[1] https://www.tate.org.uk/art/art-terms/p/postmodernism [2] https://qz.com/1388555/everyone-hates-postmodernism-but-that... [3] https://thesideview.co/journal/what-is-metamodernism-and-why... [4] https://en.wikipedia.org/wiki/Metamodernism