My brother's been a workaholic since his twenties - he's now 54, and shows no sign of changing. Let's see two divorces 3 mistress, now he's been with the same woman for about 7 years, she's equally a workaholic, so it works for them.

Personally if he's like this in his 30's and owns his own business I think he's unlikely to change. if you decide you can live with it develop your own life outside of the relationship, be that through work, volunteering, hobbies whatever just don't stay isolated.

--splitimage