What a good idea for a thread, Mario. Great idea.
RE: Loverboy. I think it was ultimately, the weak link after years of flawless uptempo lead singles. From Dreamlover, you had Fantasy, Honey and Heartbreaker and they were all incredible pop/R&B classics with incredible melodies, hooks, samples and vocals. The chorus of Loverboy is just in no way as catchy or memorable. As mentioned, she is also slightly mumbly and cooing her way through the verses as well, making it hard to hear. The rappers as well, were very heavily plastered into it and not in an organic way. I actually like their verses but if people were getting fed of that on her songs, Loverboy was an aggressive reminder of it.
The video as well, didn't help. It is, even for Mariah, very in your face. If people had been complaining about her image of late, this was the nail in the coffin. S!ut dropping, scarves for a bra, waving her arse to camera and the blonde hair that made it look like she was trying to compete with the younger generations Britney and Christina's.
Loverboy isn't a bad song but ultimately, I think it marks the clear beginning of the golden run of 90's perfection ending and Mariah not always getting it right. From this point onwards, you'd see her creatively misfire just as much as she'd get right on the money with a moment of genius. It happens to everyone. you run out 'luck' or whatever you want to call it. The fact it took Mariah well over a decade for that to happen though shows you have talented she is.