Honestly Tim cheating has been blown out of proportion.
Tim Drake’s hasn’t actually cheated in his comics. He has been accused of cheating twice and was once surprise kissed by Steph while dating another girl after he told Steph he has a girlfriend. That being said, Tim having messy relationships is a defining character trait. He struggles to balance his obligations as a hero and a person; work life balance is not in his toolbelt.
He has never had a romance go well and he shouldn’t start now. He will forget your birthday, dinner with your parents, your favorite flower, and if you’re allergic to peanuts and he will not apologize. He’s busy saving the world.
Tim Drake shouldn’t cheat on Bernard. He should miss six dates in a row to save New York from a herd of ManBats and have a weird situationship with another hero where they play flirt for six months. But when they ask him on a date, he should say “sorry I have a boyfriend” and then dream about them in a totally homoerotic way that’s weirdly platonic.