So, if you had recently copied a bitcoin address from somewhere for some other purpose, your paste would have pasted that older address from your clipboard instead of the new one that you were attempting to use.
It is very possible and it happened with me few times though I was lucky enough to have another look before sending. But here in this case, OP already stated he didn’t send fund anyone within last few days. Therefore, it's sure that OP has been infected with malware; not a mistakenly copy/paste.
Probably you have missed this-
i had no transaction within last few days other than the one i sent to my friend. i didn't have any other bitcoin address around at that time.