I agree that this example is not standard English:
In the normal sense, the present simple is used with love (i.e. He loves her very much.), although I'm sure there are a few exceptions out there in the world.
ex)He is loving
Clara very much.
I looked at the lyrics of this song, and to be honest, I don't think it sounds correct in the song, either. Sorry!
But what about the Scorpion's popsong "still loving you"? I've rarely heard of "loving you..", but I don't think it's impossible.
NO - this is where I completely disagree with your grammar book! All of the sentences listed above sound perfectly correct to me, particularly if used in spoken English. In fact, when written as many grammar books suggest, they sound very formal:
My grammar book also says even for perceptional verbs, you can't use ~ing when it's referring to temporary progressive state like below.
my English class more and more these days.
ex3)The baby is resembling
his father more and more everyday.
ex4)I've been wanting
a new bicycle for some time.
but is it true?
ex2) I love my English class more and more these days.
ex3) The baby resembles his father more and more every day*.
ex4) I've wanted a new bicycle for some time.
*This should be written as two words.
I think this is one of those times when the grammar books are prescribing what they think we are supposed to say, rather than describing the way people are really talking these days! (In other words, you are right to question your grammar book! )