The living together part is probably a reference to marriage clauses - In many countries, you are legally demanded to live with your partner and provide mutual support after you marry - Unless you have a decent justification as why you're not living together. I think that's probably what she meant.
Whoever fights monsters should see to it that in the process he does not become a monster. And if you gaze long enough into an abyss, the abyss will gaze back into you
