Ariana Grande appears to be getting serious with her rumored new boyfriend, Ethan Slater. The pair have taken a big step in the blossoming relationship after they were seen in New York. The Thank U, Next singer is currently filming for her next silver screen venture, Wicked, in the UK. But the celebrity seemed to have been given time off for Christmas and New Year, as she was spotted back on home turf. Recent photos of the couple appear to show the celebrity couple are moving in the right direction. Ariana Grande and Ethan Slater take their relationship to the ‘next step’The duo were spotted o…