Is it a red flag or just his perspective?

I'm afraid to fall in love because I'm afraid of falling for the wrong person. There’s a guy I really really like and I'm friends with his brother as well. His brother and I are close and we talk about my feelings for him too. I'm falling in love with him and his brother is basically telling me I'm being dumb. They have a lot of rivalry apparently and I don't know if it's because they hold grudges against each other or if that's who he truly is. For example, he says his brother says he's prideful but with me he apologizes when he needs to and he's letting his guard down with me. I know people deal with people differently based on their relationship with them and I think that his opinion is biased but it's my first time being in a situation like this where I'm this close to loving a guy and I'm conflicted as to whether i should run or not.

Updates
1 y
Oh my gosh, his brother has a girlfriend😐 we're literally like siblings and don't see each other that way at all😐 he's like my annoying brother most of the time and he knows it
Is it a red flag or just his perspective?
Post Opinion