I'm 23 and perhaps have not created much until recently, but now I am in the early stages of authoring an HTML5 book (on top of my day job) at a publisher's req

I'm 23 and perhaps have not created much until recently, but now I am in the early stages of authoring an HTML5 book (on top of my day job) at a publisher's request. I feel I can already relate to this. But there's something that to me may be worse than what the author mentions. It's with misfortune that I admit while I think I can deal with the stress of day-to-day programming while creating this book, I fear my girlfriend might go crazy (figuratively) in the meantime. My own emotional stress I think I can handle. But how do I deal with the emotional stress of those around me? The people close to me are very dear but I'm afraid it may well end up being a third job.