Being blamed for something which was nothing to do with you!

So, about 2 months ago one of my bestfriends, who I've known a few years tells me he likes my cousin, so me being the nice person decides to try and hook them up.
It works and they get together.
They're together for about a month and it's all happiness.
But suddenly this week it changes, he doesn't talk to her for 5 days, ignoring her calls and messages then suddenly he decides to get intouch. Then the next day we're all in the pub as the sun is shining. We're having a laugh and enjoying ourselves. He admits to me he really likes her and things like that. I give him the warning of "if you hurt her I'll kill ya" because she's more like a sister than a cousin and I look out for my family.
Anyway they plan to go out the next day just the 2 of them which I thought would be good for both of them as usually me and his brother are about (me and his brother being an on/off item). Anyway it came to the next day and he doesn't get intouch, my cousin tries to get intouch with him but no answer. I was a work at this point so I didn't know what was happening.
The day after that my cousin comes round in tears saying that my bestfriend had basically said it isn't working, and called off the relationship. None of us understood why as it seemed to be working, even though he worked nights alot... but it worked.
Tonight I went out with a few friends and my cousin when my "bestfriends" cousin and other brother came in. She told my cousin that my "bestfriend" was saying it was my fault that the relationship ended, because I was always around!
I got really pissed off with this and rang my "bestfriend" as soon as he realised I knew what had been said he put the phone down.

I just dont understand where this has all come from, how can I get the blame when the only time we had seem him together is when me and my cousin had planned to go out. Also I'm getting the blame for "always being around my cousin" when he never left his brothers side, his brother was constantly around aswell!

I really thought he was a good friend, but now that he's blamed me because of his failed relationship with my cousin, I think it's out of order. I'd of done anything to make sure my cousin was happy and I did.!