Being rude or just minding my own business?

I had a crush on a girl at my college she was new and I wanted to take my time with her and get to know her slowly and just overall be friendly. (The reason why I didn’t get her, taking time).

So she’s dating my bestfriend who, in all honesty, I and few other friends of the new girl, believe he doesn’t have what it takes. Now it’s not all said in hatred. Yes he’s still my friend but personally I find it hard to talk to him or her.

The problem is I’m wondering whether I am being outright rude to them both. For example(s), when I see them walking together towards me, I either ignore them and walk past or turn the other way. Another one is that, we are on the ferry together and I ignore her. Again, this isn’t done in hatred, I just can’t converse with either of them. I’d like to know if this is being rude. Because all I want to ‘say’ is that, I’m happy for you two and I don’t want to be involved anymore. Thoughts and criticisms?