Even if your loved one is so befallen with guilt about the crime he or she has just been arrested for to the point where he or she doesn’t want to pay for bail, you, as their supportive loved one, should not let them sit there in jail for what will seem like forever. They may tell you not to help them bail out of jail, they may feel guilty for having you spend this money on them. But don’t let it be their decision (they’re not thinking straight). It should be yours, to help them bail out of jail.
And you don’t have to pay the 100% cash bail. You can definitely go the more flexible and affordable route of bail bonds, where you’ll end up paying only 10% of the cash bail, and over a longer period of time.
At some level, your loved one will be glad you didn’t listen to him or her and helped them bail out of jail. They’re just being hard on themselves; you need to show them that they need to keep their heads and hopes held up.