Help with leak

Hello
I have a narrow Kenmore built-in dishwasher model #587.14439200. On the inside of the washer tub, right where the water fill tube comes into the tub, there is a small plastic ring, that goes around the water fill tube. The other day that little plastic ring broke off, and immediately after that we had some water on the floor during a wash cycle. My wife seems to think that the water spillage is from that ring being missing. I have looked on many online sites that show an exploded parts view, but none of the sites that I have went to, show that piece on their exploded views. I can’t even find a part number for this part. Is this little ring needed to prevent leaks??? Is this ring necessary as my wife suggests to prevent the water from leaking back around the water fill tube?? Since I can’t find this part, I’m hoping that someone out there might have a part number for this piece, or know where I might be able to find it. If anyone can steer me in the right direction to locate one, I would very much appreciate it, and so would my wife.
Thanks Dave

Your wife were right - this part is important to prevent water leak.

You were right as well - this part is not shown on the diagrams and not listed anywhere. Unfortunately that means this part is no longer available.

Gene.