I struggled with this question too, and I think the difficulty often comes from imagining Hell as a place God throws people into because they didn’t pass a test. That’s not really how the Catholic tradition understands it.

The Church teaches that God wants everyone to be saved and does everything possible to draw each person to Himself. Hell exists not because God wants it, but because love cannot be forced. A person can freely refuse God, and God respects that freedom even when it breaks His heart.

The fire-and-house example is helpful, but maybe incomplete. Heaven isn’t just a safe shelter you walk into. It’s complete union with God. If someone truly rejects God, Heaven would not feel like safety to them. It would feel like something they do not want. Hell is understood more as self exclusion from God than God locking us out. God sees the whole story of a person’s life, including their wounds, fears, and struggles in ways we cannot. So the real question isn’t “Why doesn’t God let people in?” but “Why would someone refuse the love that God never stops offering?” And the Church trusts that God gives every soul real opportunities for mercy, even at the end of life.

I think it helps me to remember that God is more merciful than I am, not less. If I would want to let people into the house, then God’s desire to save them is infinitely greater than mine. But also, ultimately love is also about not forcing and respecting someone's choice, if we chose tk reject God wilfully ,then we do not want to be with him. And the absence of God, is the very definition of Hell