Should she get another rat?

Ok so my friend thinks she needs to get another rat. Within the last year or so she has boughten many rats.The first one, Chester, lived for a long time and died of old age. Then she got 2 more keiko and yuki. Yuki died soon after she got him and then she got a new rat jiro. After this Keiko died and she got a new rat Teddy. After this Jiro died and now she wants to get another new 1. I'm telling her not to because there seems to be a pattern going on here. But she says it is just because of her bad luck. She is concerned that Teddy will die from depression becuz he is lonely. I want all you rat experts to decide if she should get a new rat to be w/ Teddy or just stay w/ Teddy and not get a new one. Thanks!