经常看美剧/综艺/小说时看到如下场景使用convenient，我知道直译应该是方便/便利/合适，但是觉得还是不够贴切，总觉得脑子里面应该有个更贴切的翻译，但是怎么也想不出来？
比如下面这个场景:
A：“That was really quite desperate of you，tricking her into drinking your blood so that she became attracted to you.”
B：“Unlike you who fed your own blood the very night you met.”
A：“How do you know that？”
B：“So you're not denying it？”
A：“I was saving her life.”
B：“Isn't that convenient？”
这里的人物B暗指A开始就设了局让她有生命危险再喂血，how convenient？

其他的场景无法写出具体的台词，但是大致都是为了达到某个目的从而编出一个理由，然后被别人识破说that's convenient，然后被识破的那个人通常听到了之后就会恼羞成怒了。

到底翻译成啥最好？凑巧？方便？合适？