Writer: how to draw borders around individual paragraphs?

I use borders to emphasize important or summary paragraphs. I am quite satisfied with the fact that a single box is drawn around consecutive paragraphs sharing the same style. However, recently, one of my documents exhibited two adjacent paragraphs (with the same style) which should show as separated since the second introduced a break in the idea flow (whereas usually the second was only an extension of the first).

I could, of course, create a clone paragraph style to deceive LO, but this is not satisfactory because both paragraphs belong to the same “semantic level”. An other workaround consists of inserting between both an empty paragraph with minimum font size, i.e. 2pt, and 0cm above and below, but spacing cannot be set really small and this is not satisfactory either.

How can I prevent border merging for two consecutive paragraphs with the same paragraph style?

Did you regard the ‘Merge with next paragraph’ property on the ‘Borders’ tab of the editor for paragraph styles?
To get the middle border lines separated you will also need extra space above or bleow.

I am ashamed, I should have considered this option. It solves the problem but I must think now about its seamless integration in my style set (where I try to avoid manual formatting). Thnks a lot.

We might better not dwell on being ashamed.
(I personally would consider to use one-column-tables or a frame style for the purpose instead of complicating my collection of paragraph styles. You may use any paragraph style inside tables and frames.)