The heart keychain in question is supposed to represent friendship. In Japan, hearts are used for friendship, unless you want to think Kazuma wants to have sex with Haruka because of the hearts?
However, here's a real song that was featured in a Sonic game... ^__^
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The lyrics were not used in the game, NON-CANNONBALL. Dreams Come True was picked because most of their songs (All?) are love related, and Sonic was originally supposed to be with Madonna. The deal with Dreams Come True was already signed, they started making songs for the games before Tails was even thought up, unless you want to think they were aimed towards Robotnik?
The first time the lyrics were used was with Elise, Sonic never ran from her, he only runs from Amy because she is annoying and wants to force marriage upon him, this is a common gag seen in animation. It has nothing to do with suddenly wanting to have sex with your best friend.
Notice how he actually always comes running to save Amy in the games? He never helped Tails in most of them, in Sonic Unleashed he was actually shy around Amy when he was a werehog because he did not want her to see him, he did not care what Tails thought of him.
Sonic also got along really well with Rouge in Sonic Battle, and he seems to be really good friends with Cream too.
Also he is a cartoon character and you are a gross fuck.