Florence, 24, took to social media to post a lengthy video addressing the ''horrid hurling abuse'' she has received since posting a birthday tribute to the 45-year-old actor, from trolls who have criticised the 21-year age gap between them.
In her video, the 'Little Women' star said the abuse forced her to switch off the comments on the post as she doesn't want her Instagram to be a ''toxic'' place.
And now, singer Ariana Grande has offered her support to Florence on her own Instagram account.
Commenting on the video, the '7 Rings' hitmaker said: ''Oh I love and appreciate you so much,'' before quipping she would be getting ''being hateful is not trendy'' tattooed on her chest.
Ariana then expanded on the situation in her Instagram Story, where she posted Florence's video and wrote: ''Sharing special, personal life things on the internet can be truly traumatic. I just wanted to share this and let you know how perfectly u expressed this and how appreciated you are for doing so (sic)''
The 26-year-old singer - who has had high-profile romances with the likes of Pete Davidson and the late Mac Miller - has since deleted her Story post, but re-shared Florence's video without her own comment.
In Florence's original video, she slammed trolls for ''bullying'' the 'Scrubs' star, and insisted no-one has the right to tell her ''who [she] should and should not love''.
She said: ''On Monday, I posted a photo in honor of Zach's birthday and I wrote a birthday message underneath.
''Within about eight minutes of the photo being posted, I had about 70 per cent of the comments hurling abuse and being horrid - basically bullying someone on my page.
''It is the first time in my entire Instagram life that I've had to turn off the comments on my page.
''I've never been an Instagram page that encourages that. I've never been an Instagram page that likes that toxic vibe.''
And later in the clip, she added: ''I do not need you to tell me who I should and should not love and I would never in my life tell anyone who they can and cannot love. It is not your place.''
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