I just Dont Know - "My partner of 3 years has heaps of accounts to singles hook up sites"

My partner of 3 years has heaps of accounts to singles hook up sites, we use to look at one together but now hes got heaps with his own name and details an they are with his new email so he can't tell me they're from before we meet.

But when we started he was engaged to an older woman with a daughter i think i was just meant to be a fling i tried to walk away and now 3 years later we are engaged.

I feel like he has his secret hook ups on the side, we use to work together and be with each other 24/7 now we seem so distant although our sex life is still fantastic and he still tells me who hes been talking to when he comes home...

Should i be worried about these sites?