So far Natsume hasn't told the couple or his 2 friends (forgot their names atm) but Tanuma and Taki, and someone else know. He might tell them one day but the missus may be catching on that he is able to see somethings, however it was only shown once during the chapter about 2 crows. Fairly certain she believes he can alas I have to read it again.
I'm pretty sure the couple knows deep inside that natsume see the things they can't. The 2 crows mentioned and this one part where natsume sorta blew up the room like his grandmother use to do in the past at his current house. I guess the couple don't want to pry into natsume's business until he is willing to open up and talk to them about it.

I started reading a really long time ago and did not catch up with the updates yet...
Will Natsume ever tell the Fugiwara couple/his other friends about him seeing ayakashi?
Or if he already did, in which chapter?
Thanks (●'◡'●)