http://www.youtube.com/watch?v=fIsKapR47wM ~ However, this song has been used for L and Light as well as Hellsing. But, meh, it might still work.
http://www.youtube.com/watch?v=IiOZggBGUAk ~ This song also comes to mind, but it doesn't really give the nice underlying warm fuzzy feeling, but it is kinda funny.
http://www.youtube.com/watch?v=tjRmhxqWmVU ~ I know it has been used a lot, but depending on what anime you are using and how you do it, it could still work.
A few songs that don't fit quite as well, but if you are straining can take a look.
http://www.youtube.com/watch?v=bMfoXz6VMX0 ~ Is actually about fighting lovers, but you might be able to make it work
http://www.youtube.com/watch?v=nFa0E_GwJ30 ~ Is probably more comical than you are going for and is between two girls
And....yeah that is all I got, lol. Probably no help at all, but ya never know.