How does the Darcys' ruby anniversary party change Bridget and Mark's relationship?

At the ruby anniversary party, Bridget and Mark's relationship changes because they have an opportunity to spend time together where they are not under pressure from family. They share a light moment when Mark catches Bridget feeding milk to a terra cotta oil burner. They also share a private moment on the patio outside, and Mark finally tells Bridget why he does not like Daniel. Mark displays jealousy when he finds Bridget dancing with a young man on the patio. Bridget is surprised and excited when he asks her out on a date. Mark also implies that he has broken off his relationship with Natasha so he may pursue Bridget.