24 and 27 is definitely not a huge age gap. If he's working 70 hours in a 5 days, then I can see how he might be too exhausted to have sex. I think the best thing for you to do is to talk to him about it since this is obviously an important issue to you. Let him know that you know he's been working very hard and that his energy is kind of being consumed by it for the moment. But also let him know that the constant rejection is bothering you and just because he's too tired to have sex does not mean you two still can't be intimate, say like cuddling together just to watch a movie or maybe even just taking a nice, relaxing bath together. Those don't take a lot of energy, not like sex does.

And it makes sense to me to "want to be wanted". He's your boyfriend, he should want you even if he doesn't have the energy to fulfill that want.

You need to make it clear that this should only be a temporary arrangement because sex and intimacy are important to you in a relationship, as it should be. Tell him it's okay to not want sex for right now, but tell him he could still do his part in making you feel like you're desirable. In this way, I think you could show him that you understand the pressure he is under at work. At the same time, it also shows that you expect your feelings to not be neglected or pushed aside. Once you tell your part, give him the opportunity to unload his side of the problem.

I hope it works out! Good luck!