And soon they were inseparable.

They've been inseparable ever since.

It's (undesirable but) inseparable relationship

They are rather inseparable, I'm afraid.

She's at Lana's. They're inseparable these days.

Thick as thieves. Nigh inseparable, we are.

Infrastructure at that large scale is also inseparable from communication.

And those who say Our Lord! Avert from us the torment of Hell. Verily! Its torment is ever an inseparable, permanent punishment.

We solved that seemingly inseparable differential equation by recognizing that it was homogeneous, and making that variable substitution v is equal to y over x.

Say (O Muhammad SAW to the disbelievers) My Lord pays attention to you only because of your invocation to Him. But now you have indeed denied (Him). So the torment will be yours for ever (inseparable permanent punishment).