My sister (who's 17) recently confided in me that for the past year she's been in a relationship that I didn't know about. I didn't think much of it until she told me that the guy in question is 21, apparently they met back when she was 16 and he was 20 and things went from there.
My sister is a bit of a vulnerable person due to various mental health issues that she has and as her legal guardian I'm quite protective over her. Apparently the guy in question is also slightly vulnerable and has autism.
From what she's said he seems like a reasonable guy, she's supposedly happy with him and claims that he hasn't taken advantage of her or mistreated her in any way. I'm just wondering if I should be concerned over the age gap? I know this doesn't apply to everyone but you do hear some sad stories about how age gap relationships with a power imbalance have led to the younger person being hurt and taken advantage of.
I don't want to risk pushing her away by freaking out and getting anxious over all this, so I'd really appreciate some advice on how to handle this.