NBC is apparently less than thrilled with ratings at The Voice lately, so producers want to feel a little more heat between coupled co-stars Gwen Stefani and Blake Shelton.

According to Radar Online, the powers that be brought Gwen back this season because viewers loved the romantic vibe between her and Blake — and they haven’t been delivering lately. A source says, “They basically told her that they are really just disappointed in how her and Blake seem to be lacking the in the love department this season. The producers just told Gwen and Blake that they have to honor their contracts. Part of the reason that they invited Gwen back on the show was so that the two of them could let their love blossom on screen — and they just aren’t!”