If you are of the opinion that Lapis is being a bad person, please refer to chapter 15.2. She did not force Loren into debt, but instead offered him money when he legitimately needed it, because he put himself into a bad situation (such as when he forgot to save some money for the carriage ride on chapter 1). Later on, she had to spend both his money and hers on getting a ride back to town and paying off hospital fees. After that, she offered him a deal to pay off his debt where she would neither hound him for the money, nor add any interest, which is a very good deal all things considered. She's quite literally letting him clear his debt when he feels like it. I see no outright ill intent so far.
My guess is that, due to their current status as a copper-ranked duo with little prospects of finding a decent party or well-paying quests, Lapis fears he will eventually abandon her in favor of finding a different party, as an uncompromising mercenary would. She keeps subtly increasing his debt by investing her own money on his well-being and equipment, thus guaranteeing that he sticks around at least a little longer. I'd say it's a more dynamic situation than Lapis being unrealistically charitable with a person she's met a day ago. You could argue that she could just "hire" him as a mercenary but he's still penniless, and he's lost his sword after the goblin quest, so they'd just end up in the same situation. He never once had to accept her loans but he still did, so it's still on him.
tl;dr though she's slightly manipulative, she's keeping him out of poverty in exchange for companionship.