At first glance it doesn’t sound bad to tell other people that you own Bitcoin, but there are some details to keep in mind:
Telling all of your friends might not be a good idea
I'm even nervous about telling my wife. Since there is dilemma. Eventually the prefix "ex" can be added to wife ... but then again, anything can happen, so many people are passing away unexpectedly... I don't want to have that happen and my Bitcoins to disappear with me. Looking for the middle ground, but didn't find yet, sighing.
I have some agreement with you in that, you do not really want to create incentives with anyone whether it be a wife or otherwise that you are worth more dead than alive, and it is a bit sad to be in a close (intimate) relationship with another person in which you cannot feel sufficiently comfortable that she might want to kill you in order to be able to live in a way that she perceives to be better.
Personalities are going to differ - that's for sure, and there are some people who are completely trustworthy because they have in-built limitations, and other people might either NOT have such limitations or they might feel that some circumstances justify their behaviors to go beyond certain boundaries that others would not so easily cross.
So, yes there could be some financial vehicles that are available that do not reveal all of the details of what the wife would get if you were dead.. but still allow a way to pass the coins upon such death, were it to occur (hopefully by means that are not attributable to the conduct of the wife or any of her potential agents).