Is he a sex maniac?

I recently met my boyfriend at a friend's party and we’ve been having a very passionate affair. We make love most nights and don’t get out of bed until late at the weekend. 
Recently, I was given a challenging responsibility at work and needed my sleep more than sex. A few nights ago, I woke up early in the morning to find my boyfriend masturbating next to me in the bed. 
I didn’t let on I was awake, but I was shocked. We’ve been having so much sex I feel insulted he couldn’t take a break for the four weeks my work-load would ease. 
Is he some sort of a sex maniac? 

It’s often difficult for women to understand some aspects of male sexuality. For many men, masturbation is a regular and often daily thing, no matter how much sex they’re having. 
This kind of self-satisfaction has little to do with emotion and is not meant to challenge your relationship. Some men see it as a way to satisfy an urge, like scratching an itch. 
While men can become aroused easily, women need adequate stimulation as well as the emotional side. If a woman’s brain isn’t tuned in, then she won’t feel turned on, no matter how technically good her lover is.
This is why romance and fantasy are important for women. 
This makes it harder for women to understand how a man can simply pleasure himself without   it meaning something.
You need not be threatened by his action. Research shows that men having lots of sex in satisfying relationships are more likely to masturbate than if they’re single. 
Fantasies and thoughts of their lover fuel their sex drive so they have more pent-up sexual energy to work off. So feel flattered, not insulted.
(Bunmi Sofola)