First of all the song is called "Every Girl" and it speaks about numerous types of women they like, and how they'll fuck the whole crew, and they're groupies. As you can hear he says "I wish I can fuck every girl in the world" in the video (that's in the song). I am thinking he said that shit simply because she's attractive. I Don't think it was on something personal or in reference to a relationship, I think he saw those pictures and expressed his internal thoughts. Jeremiah said her name in Birthday Sex...is she dealing with him?
I'm sure you've read about Busta Rhymes talking about how sexy the pictures are, and countless celebrities.
Also in the song they name many stars which includes:
Sanaa Lathan
Megan Good
Angelina Jolie
D. Woods
Paris Hilton
Miley Cirus
Also I still am not 100% on him saying Rihanna for the simple fact that Drake's verse is definitely talking about Brianna. I don't think Rihanna has to jump up and down to fit her ass in her pants.
The song: https://www.youtube.com/watch?v=FmhRIeo15sg