When do you give up on a book?

Don't you find that books are like lovers. Some you cant bear to be parted from, spend each spare moment in each others arms, share intimate secrets as the relationship deepens and you are changed but heartbroken when the relationship has to end and you both go your separate ways. Yet with others, after the initial excitement of the first date and the promise of the pages to come, it fades, you find excuses not to read, when you do its for less and less time, you get distracted by other books and even start to read them even while reading the other.

Sadly this is happening with The Master and Margarita by Mikhail Bulgakov. It had all the signs of the great read; political satire, Gothic appearances by the Devil,suppressed by the Soviets, but... but. I have faded and lost my way by reading The life and times of the Thunderbolt Kid by Bill Bryson. And 10 minutes ago got hold of a copy of Godless for God's Sake by David Boulton (its a Quaker thing) which will pull me further away from it. So am I on a break or is this the end for us? Only time will tell but always more books in the library who I can cherish and love...