Why don't we leave, then?" he asked. For a moment, Luo Binghe couldn't manage to react. "Leave?"

Shen Qingqiu nodded. "Didn't you say that you weren't welcome here? Then let's leave and go somewhere that does welcome you." He added, "This time, no matter where you wish to go, this master will accompany you."

So the main story is finished. All that's left in Book 4 is the extras and side stories.
As someone who doesn't really enjoy isekai / transmigration stories, I was worried that I won't be able to enjoy this story, but I supposed SVSS proved me wrong. 
I enjoyed it thoroughly, with SQQ's unserious and unhinged monologue, it gave this novel a "light" feeling, although it's not. 
And poor baby LBH, he's such a pathetic (in the most adorable and fond way) ML, he suffered so much that he has multiple issues like praise kink, low self esteem, abandonment issues, and everything else in that category.

But now that they're "Always Together" as the final chapter implies, I believe LBH will see the sun shine again, and congratulations to SQQ, for you know, coming out of the closet after being in denial for 2 ½ volumes LOL.