When setting the field 'Required' on 'true' (tick it), you expect the relation (in this example news - keywords) to be required.
But when making a news item and NOT selecting any keywords (to be linked with the newly made relation facet, in this case 'Nieuwe relatietest Marcel'), you can just save the news item, without selecting keywords. The field 'Required' does not work.
Tested on the Integrated49 environment. Still does not work.
Retest after design change