AceShowbiz -

Blac Chyna will do everything she can to trademark the name Angela Renee Kardashian, after the Kardashian sisters have successfully blocked her petition. Blac's attempt to secure the name has been denied, even if she walks down the aisle with Rob Kardashian. And now the trademark denial has reportedly added more drama to Blac and Rob's complicated relationship.

"Her not being able (sic) to use Rob's last name may have been the last nail in the coffin in their roller coaster relationship," a source tells HollywoodLife.com, before adding, "They were already on thin ice at best but now it's going to be really hard to see her marrying him." The source continues, "Rob is an emotional, depressed mess. Chyna cares for him and he is the father of her baby girl but there isn't much in it for her to marry him at this point."

Rob and Chyna officially called off their engagement in mid-February after months of fighting. They have since been feuding over a legal custody agreement of their 4-month-old baby girl Dream Kardashian. While they agree to raise their little girl together, the two allegedly have different parenting styles.

"Rob comes from a family of women who lived the better part of their lives on camera, and he doesn't want that for Dream," a source tells the webloid. "He doesn't know what tricks Chyna has up her sleeve but he's not at all interested in her pimping out their child in any way for money or fame...especially after seeing how it's made his sisters act." Rob is apparently afraid of Blac putting Dream to work after she has reportedly requested work permit for her son, King Cairo.