Noctis watches as Gladio and Prompto fall more and more in love, keeping his feelings for Prompto a secret.

A Prince can't have everything.

Give me affectionate and in love Promptio with Noctis watching heartbroken. If you want Noctis to confess that's fine but please don't have Prompto leave Gladio for him. Whether Ignis knows what's going on is up to you.