Maybe i’m crazy but i can hear him say the s. He says it quick but you can hear it.

I am hearing “ché pas si je t’aime,” which might be what you are hearing and describing.

“Ché pas” is described as a “Déformation de ‘je ne sais pas’ ” at the cited Wiktionary link.

He is singing ché pas. The phrase je ne sais pas is often pronounced ché pas in colloquial speech because it is easier and faster to say. You could compare this to gotta vs have got to and gonna vs going to in English.

In spoken language, words or phrases are often cut short to facilitate speaking. Have a look at this answer for two more examples.

“Je ne sais” is often pronounced in french as “Chais”.

Many french people will say “Chais pas” instead of “Je ne sais pas” when answering quiclky, it’s very common.

As a French person, it seems so natual that I’ve never really thought about it before.
I mean, “Chais” doesn’t mean anything alone but it’s very common when you talk.

Phonetically, this is simply because the sequence of [ʒ]+[s] is almost guaranteed to result in assimilation. This section of the article in particular outlines the hierarchy up which sounds tend to move.

Ultimately, it comes down to the fact that those two fricatives are pronounced at very close points of articulation within the mouth and the natural tendency to merge them once the schwa has been elided is very hard to resist.