I just can't picture Leandra saying "thank you" to Gamlen for losing what was legally her inheritance, thus forcing her children into servitude to get them into Kirkwall; then being allowed to live in his shack. From one perspective it wasn't so bad Leandra left because that left everything to Gamlen; legally or not. Is it wrong that she left because she loved someone who wasn't socially acceptable? She would have been content to stay away forever and let Gamlen have the estate to himself before he lost it but the blight forced her back. Does that make her a bad person? Gamlen was like the caretaker of a mansion who accidentally burns it down, and then lets its owner live in his shack. Should he be shown gratitude? The situation would be different if the estate was legally his. He's still responsible for the Amell's assets but he'd be less so than when it's not legally even his.
It took them a year to find grandparents will. Were they showing at least a bit gratitude towards him before finding out about it? No. Leandra was convinced that her parents left her nothing. So they were all sure that he lost what was legally his and saw how poor he got. And yet, they all had no problem with living with Gamlen for his money, just because they had to work for someone? And I'll say it again. It's not like they were actual slaves, but they had profits from working for Meeran/Athenril as well. So what does it say about them? Sure they got nice excuse for dispising him when they found out what really happened, but fact that their attitude towards him from that point onwards was exactly the same as before is certainly not right. They were treating him bad from the very start and I find no excuse for that.
Of course she should not thank him for losing all money. It was his biggest fault and there is no doubt about it, but he did give them home even if he didn't have much at the moment of their arrival. Even if he ended there because of his own mistakes, doesn't that count for something? No matter the circumstances without his help they would not get into city, regardless of his wealth.
I never said she was a bad person. But I certainly see her as selfish one. I am not blaming her for choosing own happiness over the family and I know that she had no chance when it comes to coming back. What bothers me is only her attitude towards that whole thing. Does she even admit that Gamlen had it difficult? She should at least thank him for taking care of their parents when she could not do it, but that's a bit different matter and I did not mean that when I was talking about being grateful.
After getting back the estate, wouldn't it be nice of her to be like: "You know Gamlen, despite all the bad things which happened, thank you for not sending us away, when you had the chance." Like seriously. That would make her and all that "love is more important than money" attitude so much more belivable.