why not tell him "D" asked you for a date? maybe drink or coffee as a thank-you for helping you with the car? or tell him "D" asked & you joined him, just for coffee.
here in US, i'm not familiar with the term "sanitarians".
"Perversely, Krista demanded absolute monogamy from me. She was (and still is, though better controlled) insanely jealous whenever it came to me and other women."
that describes my wife, perfectly.