Lord, I can't even imagine having one man interested in me, let alone half the island.
Ali tells Mack she's just not feeling the spark between them. Mack is confused because HE feels the spark, therefore the spark HAS to exist, right? Mack, sweetie, she's just not that into you.
He then very sweetly tells Ali he hopes she finds that spark with someone and she cries, and he comforts her while looking completely broken-hearted. Ahh, young love. It's tough two days into knowing someone when they reject your whole damn future together.
But in a plot-twist: Ali also tells Michael she's not feeling the spark there either. She gently returns Michael and Mack back to the adoption pound, where they'll hopefully find their forever family soon. It's just not with her.