Why does boyfriend have a picture of me as his wallpaper?

[Mimi]

We've been dating for 6 months now. I'm his first girlfriend. I looked at his phone gallery and noticed there is a picture of my profile picture on Facebook . He hardly ever goes on Facebook but he finally went on. He had a picture of me and a picture of us at dinner. Both that he took from my Facebook photos. My friend said that was weird which i started thinking if it really is weird or normal. Days later, i look at his phone and it is a picture of me (my profile picture) as his phone wallpaper/background. My friend thought it was weird and started laughing. Is that bad/normal? Also another question, would a guy still do this even if he liked another girl or someone else?