I'm pretty sure this interpretation is obvious, but if you still don't understand..
This whole song is about "hoes" leaving loving guys because they can't give them all the material things a rich guy could.
"Nigga, that's that nerve
why give a bitch your heart
when she rather have a purse?"
^^Once again, this emphasizes that there are girls out there that would pick an item over love. This is Lil Wayne's part, where he rants about how he doesn't trust these hoes.
Then you have Chris Brown on the other hand, who plays the rich guy stealing less fortunate guys' women.
"Just got rich
Took a broke nigga's bitch
I can make a broke bitch rich"
Then, there is also Tyga, who raps about hooking up with these girls but they are still hoes and he doesn't believe them.
"Do it too good when she ride that dick
Man I wouldn't trust that bitch, no!"
By the end of the song, Chris has changed his tone and is more on Lil Wayne's side, saying that these hoes AIN'T loyal.
"When I call her she gon' leave
and I bet that bottom dollar she gon' cheat"
To sum it up, the entire song is about girls with perfectly fine men leaving them for the wealthy, and that's why it's called "Loyal" because it is talking about how these chicks ain't nothing but gold diggers.
