Consent doesn't make it right or moral. In fact, consent is over-rated. People consent to destroying themselves all the time. Treat others well, do good. Know when to stop somebody from destroying themself, and don't destroy yourself either.
So, no. Something wrong there. She's asking me to go against my conscience and do something detrimental to the relationship.
Monogamy is what I believe works best for the majority of society. People are complicated enough as it is. I say complicated, not complex.
Complex usually to me has a connotation of logical, complicated is closer to illogical.
The world isn't exactly advancing very quickly now, improvements technology wise in the western world now are very incremental compared to what they were in the last 100-200 years, while social improvement is down in the drain. Back when monogamy was universally accepted as the standard, even with all it's flaws, the breakthroughs in science and technology were far greater than now.
Should probably read up on the anthropologist J.D. Unwin's data on monogamy and how societies without it tended to be destroyed within 3 generations (30 years is what he considered a generation). Monogamy took away the question and energy people put in to thinking/looking for sex and so they put that energy into improving their lot in life instead. In case you're wondering, Unwin wasn't religious.