You're walking a fine line here, and I don't envy you. On one hand, my wife and I share in almost all major decisions--I respect her opinions and generally pay attention. In this case, though, I might resist, if not now, then certainly in September when it starts getting dark early.
For the record, though, are you wearing reflective clothes, with lights or at least reflectors on the bike, and doing what you can to protect yourself? I'm surprised every year at the number of dumb@sses I see riding at night in black tights and dark jerseys, with no lights or reflectors. Those people DESERVE to be hit....