This guy wont move on!?

ok so I found out this guy likes my friend, and he has for a while. But then earlier in the year, he started to like me, I told him I wasnt interested, so he went back to liking my friend. But she likes somone else, and he knows that! And now he's like, writing songs and poems, and my friend is getting annoyed by it, what should i do??!!!!ANd he is the type of guy who is super sweet abut has the mpst ANNPYING SIDE EVER!!!!! Thanks in advance guys!