Can someone explain this too me?

I have been with my fella for 6 yrs and he suddenly wanted to break and play around. he is out every second saturday night and i can't reach him.then he started pestering me again to meet midweek for .i said no.he says he will think about coming back into the relationship but not yet.we both need a change and should date others. so i get my cousin to text him.she used to get on well with him, and he is alot more responsive to her than me.then he asks me if her and I have any nights out planned.why is this?