My sister is fucking stupid

So my area has been on a stay at home order for about a month now and I just found out from my mom that my sister (who still lives at home) is still going back and forth to her bf house. Like wtf. Her bf work at my job in a healthcare facility but in a different dept. I can’t believe her dumb ass is still going over his house daily. My parents are 60+ and my dad is fucking diabetic. This is infuriating. And of course I feel like I can’t say anything because she already doesn’t really talk to me (ever since she started dating this guy a few years ago) and if I do say something she’ll get offended whether I say it nicely or not. People like her are why this shit is spreading and I can’t believe she is acting so stupidly.