Need help figuring out fair-equal coverages. Any help appreciated

My girlfriend and I are going with different providers.

I am mid-40s and make ~$150k, but it fluctuates. She is mid-30s and makes ~$100k with a union job. We have a 2-year-old.

I am choosing a $2M, 30-year-term for ~$260/month.

She is choosing a $2M, 20-year-term for ~$160/month.

We are arguing because I am covering her/my child for an extra 10 years (into my 70s), whereas her coverage ends in her mid-50s.

She tells me that she wants to convert her new term policy to whole life before in the next 5 years, so her rates don’t change, which would mean me/my daughter would be covered longer than 20 years. I am trying to tell her that probably won’t happen because whole life will cost her 2-3x more/month and she’ll probably balk when they send her the paperwork. (By the way, I am not a fan of whole life policies.)

How would you balance our two policies? Also, do they seem reasonable? Should I lower mine to 20 years? Should I offer to pay the premium difference to make her term 30 years?