Although I did not have lent money to my cousin, I had a similar experience as yours couple of years ago. I lent one of my closest friends at that time around $4,000 and expected no return any time soon without any interest. I just wanted to help my friend then so I was not expecting anything from him. However, two years later, I decided to buy an apartment and I kind of needed money but my friend never wanted to pay my money back. Well, I thought maybe he was still short of money and that was fine if he would not pay me back soon. To my surprise, a few months later he was assigned a teaching job in my city and he asked to live in my place for two months for free. I thought this would help him financially so I agreed. However, he forged a lease on rent to get money from his company and kept the money. I thought he might pay back the money I lent but I was too naive. He used the money to buy a brand new camera and never mentioned anything about the money he borrowed from me. Two months later after he went back to his city, I summomed the courage to call him over the money he owed me and he was angery. Several months later he paid the money and blocked my calls since then. That was really an aweful experience and I stopped lending money since then.
I had similar experiences with two of my neighbours at different times. We weren't exactly friends, but we were living in the same multi-flat building so, we knew each other, ok. It was several years ago and both of them never returned the money, no matter in what financial state they were during this time. Are we not friends now? No way, I don't want to be at odds with my neighbours. What's the catch then, you may ask. Well, the amount I lent each of them was around $5. I will never lend them a dime in the future, but I won't be bothering them with "Give my money back either". My point is, lend only what you can afford to lose.
I also had the same experience when I lent my one of my closest friend money because her child got sick. I was a soft hearted person before and it was hard for me to say no especially if it was for emergency purposes. But that friend of mind didn't pay her debt back despite knowing that I will also be using that money to pay my bills. She ruined my trust and from that experience, I realized that lending money can ruin relationships and friendships. If you borrow money for an important reason, you should keep in mind that the person who lent you the money trusts you so you should never break your promise of paying it on time.