It would be erasing what happened, and for him, he’s just not quite ready to fully accept she’s gone.
So when the cleaning duo come[s] and he doesn’t let them in, it’s because they would be doing things like cleaning up the bloodstain on the ground.
That’s a really good description of why.
When Helen tries to reach out to him — which he’s in conflict about, it’s not like he’s against it, he knows he needs to accept help at some point — he just can’t do it yet.