what note?
The “Note” added by Douay Rheims that I have included at the bottom of the quoted scripture. It says the exact opposite of what you are saying.
The D/R Bible (which is, essentially, the original translation of the Latin, Greek and Arabic texts by St Jerome) was the “Catholic Bible” up until the Second Vatican Council. In the early 1970’s, the Modernist pope (Paul VI) and Modernist bishops abandoned that Bible and adopted the “politically correct” New American Bible.
The original word “fornication” in that specific scripture passage was re-interpreted and re-written as “(unless the marriage is unlawful)” which fit nicely into the Modernist view of so-called “Catholic annulments”. There has been over 50,000 per year since that time.
As noted, the Douay Rheims Bible acknowledges precisely what Jesus actually said––and meant. One may separate from your spouse over fornication, but they may not remarry while their spouse is alive.
Both Bibles are online.