So I spent some time combing through all of their interaction and interviews and this is the revised count that I’ve come up with.
From everything that I can tell, as of November 28, 2015 they have collectively said “I love you” publicly a total of 42 times. Individually Zendaya has said it 23 times, while Val has said it 19 times. It has verbally been said 4 times, all of which have been spoken by Val.
Side note: These are only the times when they’ve actually said it. There are way more times when it’s been implied or when they’ve thrown heart emojis around as their only reply to each other.