What is going on ?

So my partner has a job where there’s 10+ female workers. My partner is a huge liar and thinks he could get away with most of his lies . He also has a very high sex drive. Like he could Fk almost everyday if wanted to. We live together and been together for 4 years now…..Usually he’s wants to have sex everyday , even when we’re mad at times . But I’ve noticed a few changes. For the past 3 weeks , Mon-Thursday

He touches me, cuddle but we don’t have sex , if anything he’ll jack off. Come along the weekend Friday - Sunday

That’s when he’ll want to have sex. Again this coming from someone who has a very high sex drive. Before these 3 weeks he’s always wanted to have almost everyday . Now he only wants to when it comes to the weekend . In my eyes , when he’s not at work. I told him if he jacks off at work when he has the time , he said NO. He’ll rather wait till he’s home or with me. Something’s changed , he wasn’t like this . My gut feeling tells me something is off at work. I told him about it , he says no. Again he only wants to have sex now on weekends . He still touchy and all but doesn’t want to have sex . I’m I overthinking it ? Could it be someone at work?

I should note* He’s cheated before , I took him back to work out the relationship for our kids . I didn’t just want to end but now there’s this .