Shortlist return URL
As mentioned in the comments on the Question, the solution here is to enclose your desired path with a url() function like so:

&lt;a href="{{ item.addActionUrl({ 'return' : url('my-page-i-want-to-go-to') }) }}"&gt;add item&lt;/a&gt;


The url() function will take your current SiteURL and append the provided path. You can view the offical documentation about url() here.