mike cannot say "i love you" to el, even when she is breaking down crying, begging him to just say it.
he can say "i love you" to el after being encouraged by will's speech to him in the van. will's speech to him about will's romantic feeling for him.
mike cannot say "i love you" in response to el's feelings, he can say "i love you" in response to will's feelings.
mike can only say the words when inspired by will's love for him -> mike feels loved the way he wants to be by will's feelings for him -> mike is in love with will's feelings for him -> mike is in love with will. and he doesn't even know it. canonically.
that's why they didn't address the painting.

















