The problem
In Divi (and wordpress) adding page links within the body text can be problematic if you want to use a RELATIVE LINK.
Quick Method
Simply insert a link (link button) and add the page name without any slashes or path names. This can be found on the page itself or by looking at the URL when the page is loaded and using the text bit between the two last slashes.
Full Method
Also Divi provides a Page Dialogue by following this procedure:-
Go to Divi Settings in WP then ... Theme Options > Builder > Advanced
Here you will find an option to enable CLASSIC EDITOR - enable it.
To use this feature you must access the "back end" of Divi - that is the rectanges layout thing. Then locate the text bar in question, click the cog. The editor will appear (its similar bot not the same) and highlight the link txt, click the link icon. A link box appears with the URL box and a cog. Hit the cog button and choose your page from here.
MAKING A LINK
Simply insert a link (link button) and add the page name without any slashes or path names. This can be found on the page itself or by looking at the URL when the page is loaded and using the text bit between the two last slashes.