Wow it finally happened, and at the moment I least expected it. But it totally makes sense as catharsis for both of them.
They had some "sexy" moments before but they were all framed as power struggles or in connection with Maria's dhampir needs (i.e. much bloodier). This was the first time they had a more equal, more romantic romp (and, of course, sex).
On the downside I think Wataru's injury is definitely affecting his art. :/ I am definitely glad he can still continue this story for his readers but the drawings are looser and less detailed than ever. Hope he continues to recover (and saves something for a big concluding Dorothy x Maria sex scene!)