how to know if your boyfriend is cheating?

[Amanda]

My boyfriend is hot and has girls up his a$$... i hate it... but he rates girls on facebook, if i like it mine is always the highest.... but he talks to his ex's and hangs out with them and a couple of girls.... i wanna know if there are any signs that a boyfriend maybe cheating?
we have been dating for 2 weeks...

[Trisha]

check his phone..
if he spends more time with them then you
if he flirts with them behind your back

[Oki]

Everything you just said.