I’m talking to my brother’s best friend

I have been talking to my brother’s best friend for a couple months and I really like him. We see each other and spend a lot of time together but my brother doesn’t know. Should I tell him or should I just wait to see how things go and tell him later on? I’m scared things won’t work out and I will just create awkwardness between all of us. In the future I would just tell him we met a couple times and that’s it if it doesn’t work out. He’s quite protective and I’m scared he’ll think I’m being disrespectful as we do have a very good relationship. Please help

well I mean if things go further between you and his bsf (as in you end up dating) but then things start to go wrong which isnt unlikely your brother might potentially lose his bsf because of it and he will probs be upset about it and it might weaken your relationship