I can think of 2 possibilities here.
1. Not forgiving others [like we're instructed to or we won't be forgiven]
2. Unrepented Sins [believing one can sin because Jesus died for all sins]
Looking at the 2nd possibility presents several issues such as (license to sin) and the doctrine Jesus only died for the chosen [but dying for all sins would have to mean all sins period as in every human being saved or never will be saved sins].
If I walk around and expect God to forgive me but I never forgive those who do me wrong then I am nowhere like God (we are to be imitators of God and do as He did).
If I sin today and don't repent then that is still a sin that God remembers because it hasn't been applied to the shed blood that takes place when I ask for forgiveness.
There's other issues that can be mentioned but these 2 seem to be the most debated about.
Brother, either by God Father and Son, you are reconciled, forgiven 2 Cor 5:16-20, Eph 1:7, 1John 2:1-2, 3-4, 12 done once for us all at the cross, that is done is it not? Now, what to do? since, one sins again afterwards and has; all of us, and hide that too. I have and admit I am not perfect, want to be, not seeing I am made perfect by God as in Col.1:21-23. Trying to do, what is done by Son first. What is already done for me and all the world by God for us all to believe God? receive truth from God, not self or anyone else. To walk new and love all in the same mercy of love given you first 1John 4:19. as is the rest of all too by God Farther in risen Son, it is done John 19:30, John 1:29
Or, there is more to do, as if Christ's done work was not or is not good enough. on that cross. It is the risen Son where new born new life is given to all those that will not quit belief to see its truth from God Father. Which, does not get taught by people in general, trying to be right over others, then think they are being pleasing to God, as no flesh can do that now. Since by Son that is done Romans 8:1-3. And everyone sees they can't do it perfect ever of themselves or anyone else. Religion has taken the place of God's done work, over Son, done once for us all on that cross. The death was and is for being forgiven by God Father through Son, first. The death was to reconcile us all as forgiven, as if no one ever sinned to begin with. All that got left is to believe Son as risen for you to be new from God Father working it all out through you in love and mercy to all. Has God ever berated you for sinning again? Religion has, and even self, being made aware of of sin. That is how evil gets in, being made aware of sin under Law, and traps people in sin, not wanting to sin, yet do. Re-read Romans 7 and trust Daddy, PaPa, Father to reveal this truth to you, and see new as in Romans 3:31
Wait, But I just sinned again , I had a lustful thought, and God says I am forgiven still, by that done work of Son for us all (Hebrews 10:10), even though I know I have sinned again and did not want to. I did it anyways! God, I do not want to, yet I do what I do not want, I do! What is up
What? How?
God, telling us each personally to die to self, Romans 6:1-12 first birth willingly, between God and you. Anyone that willingly does that will begin to see new, being now sealed by God to see it through, Eph 1:13, no matter how long it might take to see it. Those that will not deny God. Even though upset over troubles we all go through here on earth first. Choose to not deny God as even Job would not and deeper in Jesus the Son who reconciled everything to his Father God for us to new, receive the new Life in risen in Faith belief only, Son Spiritually alive for us, as you already know all this within you too, as God loves us all, otherwise that cross would not have ever happened to begin with, to me at least, only sharing this Love of God shared with me as you do the same too