This was a huge topic of conversation in our community some years back. In fairly rapid succession, multiple estates were settled that involved 2nd wives, step-kids, biological kids, etc.
Really covered the gamut - 2nd wives disinherited by biological kids, biological kids disinherited by 2nd wives, long term care chewing up assets for everyone.....lawyers ending up with more than anyone.....Multiple estates, multiple outcomes - all bad and with a lot of heartache.
My wife was hot on the topic. She's smart and realized she couldn't keep me from spending on a 2nd wife, nor did she want to punish someone who might make me happy after she's gone, but at the same time, she was adamant that our kids be protected and have something.
She didn't want "her (our) kids' money all spent on my next wife's face lift and new tits" as she eloquently put it.
I told her "she's" already had those done and not to worry about it, which evidently wasn't as funny to her as it was in my head.
We had some fairly robust planning already, but she was so bothered by all this I finally took her to our attorney and sat arms folded and told him to draft something so she is happy enough that she'll quit talking about it.
After some time and some money well spent, she's content, and while nothing is perfect there's enough safeguards to cover everyone's interests.
Like everything else, communication and then taking action is the key.