Bond scare

My roommate and I are best friends, and we’ve lived together for four years. Recently, she got into a pretty serious relationship, and it seems her priorities have totally shifted.

Is a best friend always second place to a boyfriend? Or are they both of equal value?

— Hurt

A female best friend can do a lot to make you happy — even give you a baby — though she’ll have to wait till the NICU nurse gets busy and kidnap one for you.

It can feel like a betrayal to be downgraded in your bestie’s life when a serious boyfriend comes around. However, evolution’s ultimately to blame.

“We are survival machines — robot vehicles blindly programmed” by evolution to preserve our genes by passing them to generations after us, explains biologist Richard Dawkins in “The Selfish Gene.” Simply put, we’re each a big flesh bus driven by our genes, subconsciously steered to do their bidding. Psychiatrist and evolutionary medicine founder Randolph Nesse sums up the grim reality: Evolution “does not give a fig about our happiness.” It likewise doesn’t care whether we have friends, save for how they might help us survive and pass on our genes.

This sounds cold, but understanding the evolutionary reality can help you stay in your friend’s life and keep her in yours — perhaps without taking her shift in priorities personally. I use that understanding — despite finding kids loud, sticky, and expensive — to be supportive of friends who are moms of young kids. I insist to them (and genuinely feel) that it’s okay if they need to put off a call or drinks we’ve planned when they’re wiped from work plus momming. An important caveat: These are dear friends who show up for me if I’m in need; I’m not rolling over for a bunch of userish socio-Pattys.

You likewise might consider reconfiguring your expectations so you two can stay friends and you won’t make her feel she has to choose between you and the guy. You’d surely lose that battle — which means you and she would both end up losing. Supposedly, a truly “intimate” relationship is the sort you have with a man you love, but … well … when’s the last time coffee with your bestie ran long and you faked an orgasm so you could get on with your day?