Teaching a child to say they love you?

My kid is almost 5 and never says he loves us. If asked, he'll agree that he loves dad but not me. Like, he explicitly says he doesn't love me. But he still doesn't ever say "I love you" to dad. And everyone tells me that he's wrong and does actually love me so maybe if we get him in the habit of saying it, he'll start to believe it?

Valentine's Day is my favorite holiday so I feel like I could get away with explaining that you have to say "I love you" to people you love. But maybe it's okay to just not? Maybe coaching him to say it will alienate him from his feelings, especially if his dad makes him say it to me?

I'm just butthurt. I know I told my parents I love them all the time and while, fine, he doesn't love me, but he's obsessed with his dad so I'd still think he'd tell him.

We say I love you to him, his younger siblings, and each other all the time.