Hi Tahar, although I agree with Anya's answer above, I feel that sometimes one needs to go beyond grammar to understand modern-day usage of the English language.
"I am loving this" is absolutely a normal, acceptable every day English phrase.
When we use the continuous form in your example, it really emphasises to me how CURRENT that thing is.
1 - I love you = always, it is a constant.
2 - I am loving you so much right now = I think that, in this moment, you are adorable and my heart is bulging with my love for you!
Despite the grammar, this would be commonly used. e.g. The McDonald's Slogan: "I'm Loving It".
Any questions?
Tom