Yes Nibbana is only permanent solution. Intense suffering would have been more often in absence of understanding of Buddha’s teachings. But understanding of these teachings mostly dilutes the intensity of sufferings. Still Too painful mental and physical state do come and go and that is when I am not being mindful ….and more interesting,sometimes even when I am mindful it stays …. … But yes happiness is still an illusion . What can make one happy other than Nibbana ? Need to look deeper into my sensations and feelings. Sense organs are not at rest ….they are still seeking and demanding but the resultant pleasure seem to be missing. May be Jhanas can bring a state of happiness?