Please note that "aimer les livres" is not "lire les livres".
Verb aimer (+ other appreciation verbs) are constructed with le/la/les for generalities
Other action verbs (lire, prendre, manger...) do not automatically introduce generalities.
In this case, "lire des livres" is just the plural of "lire un livre" (in English there is not plural form for a/an, but in French, un or une have a plural form: des).
This is a free world, at least for feelings! you can love or like anything or anyone. You may express it the way you like, depending on the intensity of your feelings and also to the expected response...
The other day, I watched a British series (a story about nobles in their castle early in the 20th century) and a man said to his wife: "I do love you so very much indeed!". I was taken aback by the number of words used...
Anyhow, in French, you will not use "je t'aime" if you have a risk of being misunderstood. For friendship, please use "je l'aime beaucoup", "je l'aime bien". For sexual love, use whatever you want if you dare. For objects, concepts, any inanimate things, you may use a variety of adverbs with verb "aimer" to qualify the intensity of your feeling: "j'adore les fraises", "j'aime bien le poulet, mais j'aime encore mieux le caviar", "je suis fou de chocolat"...
If it were singular, the sentence would have been: 'Ma mère aime lire un livre.'
Or, to quote from Sitesurf's explanation: 'In this case, "lire des livres" is just the plural of "lire un livre" (in English there is no plural form for a/an, but in French, un or une have a plural form: des).'