When the believers enter the Paradise they will say:
وَقالُوا الحَمدُ لِلَّهِ الَّذي أَذهَبَ عَنَّا الحَزَنَ
“Praise to Allāh, who has removed from us [all] sadness and sorrow. (Surat Fatir:34).
So until then, the believers will always experience many moments of sadness and grief.
Always Seek Allahs help during those moments and don’t give up on His mercy.