图个安心 = 图一个安心 图 = want 安心 = carefree All I want is leaving nothing to be worried about. All I want is just being sure that everything is ok. 我这么做就是图个安心.

图=seek for/want 安心=feel at ease/ feel at peace / feel secure Normally 图个安心 is used when you need to take some actions to make yourself feel secure and at ease. eg: 我这么做只是为了图个安心。 I did this just for comforting myself / making myself feel at ease.