should I stay or leave

there is this guy I met online we started of so nicely we are both working in different countries doing out own thing to provide for our families ,when we started dating it was all fun and giggles we could call each other and talk about stupid things and just laugh the all day ..but recently I noticed that he has changed...he posts of girls all over his social media when I ask am the nagging one ...he barely calls me and when I find time to call him ,He will give me excuses like am busy or my boss is around...whenever I decide to walk away from the relationship he tells me how much he loves me which gets me really confused ....what do I do guys coz I feel like he is cheating and not into me anymore like he used too.