I love a good romance story as much as anyone else, but something I think gets overlooked a bit is the strong bonds between two individuals in a non romantic setting. It's not always sad all the time in media, but outside of the 'I love you' to parents and love interests, it's nice to hear it from characters who have a close bond.

Stewie and Brian (Family Guy) - In one of the most liked episodes of Family Guy, Stewie and Brian end up trapped in a bank vault for a weekend. During this time they end up fighting and talking, and Stewie asks why Brian has a gun in his safe with one bullet. Brian admits that he keeps the gun just in case he ever decides to end his own life. Stewie who is shocked by this then calls him selfish and says that without Brian in his life he would be miserable. He then admits to Brian that he loves him, and Brian says it back.

Zenitsu and Jigoro (Demon Slayer): During a flashback, we see Zenitsu and his master are training and his master tells Zenitsu to not be scared and to stop being a coward about his training. Zenitsu as always is arguing with his and keeps calling him "Gramps". Zenitsu says he calls him "Gramps" because he loves him. He says that Jigoro helped him out when he had no one and took him in. And no matter how many times he ran away, cried or was a coward Gramps never gave up on him when he had every reason to.

Groot (Guardians of the Galaxy): At the end of the third movie, the guardians decide that they are all going to go their own ways. This leads to the last time they all spoke together, Groot, who normally only says "I am Groot" says in plain English "I love you guys".

[Loved Trope] The non romantic/non parental "I love you" confession