Gwen Stefani and Blake Shelton want to keep their blossoming romance "under the radar." The newly-single 'The Voice' USA mentors, who celebrated Halloween together in Los Angeles last weekend, reportedly "really like each other," but aren't ready to label their relationship. A source said: "There is something going on between them and they have spent time together off set. They don't want to label anything or define it, they just really like each other and happen to be going through similar things in their lives. Gwen has spent time at Blake's house in the Hollywood Hills recently. They want it to stay under the radar and not make it a big public thing because who knows what will happen." The duo were spotted partying at George Clooney's star-studded bash before reuniting at Jared Leto's house party on Saturday night (31.10.15). An eyewitness told E! News: "It was definitely strange for him to be there because he hadn't been in years past. They left right around the same time too. Although they were in separate cars when they left, they met up at the next party." The 46-year-old singer recently admitted she felt like she "had been living in a cocoon" before her split from Gavin Rossdale, with whom she has three sons, Kingston, nine, Zuma, seven, and 20-month-old Apollo, and was suffering from severe writer's block before they separated in August after 13 years of marriage. Blake, 39, has also been venting his emotions in the recording studio following his divorce from Miranda Lambert in July after four years of marriage. Another insider told gossip website RadarOnline.com: "Blake has also been extremely helpful to Gwen as she finishes up her upcoming album."