I'm assuming we're talking about 'Her Hero Daddy' by Chloe Maine? Because the thing is, there are a few books with that kind of title floating around on KU. The one I read definitely had a happy ending. Like, that's kind of the foundational promise of that whole romance subgenre, you know? The daddy-dom and the sweetheart get together and it's all committed and protective and rosy by the last page. But 'happy' in these books is usually a very specific vibe – it's not just that they're together, but that the power dynamic settles into this permanent, cherished structure. He's her forever protector, she's his forever good girl. The epilogue usually involves a ring, maybe a baby announcement, and a whole lot of saccharine comfort. It's a fantasy fulfillment ending, which is exactly what readers of that trope are there for. So yeah, if that's your definition of happy, then absolutely.
That said, the journey to get there can have its angst – maybe a jealous ex, some external drama, or her working through past trauma. But the resolution always, always tilts back toward that safe, owned, happily-ever-after space. It's the emotional equivalent of a weighted blanket. I remember finishing it and thinking the ending was almost aggressively wholesome, which was exactly what I needed that day.