Sons aledgedly affair.

Advice needed please do I say something to him or not.
My DD was out with friends and lots of drink was involved one of her friends who works in the same building as DS made a comment about him seeing someone, another girl told her to shut up and keep out of it. This happened at the beginning of summer and at the time DH and I thought DS and his wife were having problems.
I was only told this information yesterday as DD has heard rumours again. Every time we have seen DS and our DIL now they seem very close problems early in the year seem to be gone.
I haven't told DH as it might just be gossip from before do I say something or ignore it.
Sorry I seem to ramble so upset thinking of DGS and DGD and how much it would hurt them if they split up.