Tell me why my sister mental?

My sister, I dont really understand her at all. She's changed into someone I don't know anymore. She decided to suddenly seek out a relationship, I feel to fit in? Because she is running herself into the ground. She is on the go 24/7, has 2 jobs now and I see she is overly fatigued trying to keep up the pace of everything. She just got through some health issues and I just see her crashing before my eyes. It's not like her at all. She also is quite immature and seems to show it off a lot, I think to spite me. She also has "selective energy ", wants to go home early from work at times and get ready all to race over to his even tho she was over there , on the weekend lol Yet she has "energy ", to get ready and race over there after an exhausting day and even fuck him by living on a pathetic pill. Why she continue to fuck him? When A) she says things like how shed rather hug than kiss so why fuck his ugly dick then and b) She knows men think with their dick and if she wasnt putting out her dump her anyways. Good luck when she moves in wiht him and becomes a "pin cushion". Does she NOT realise that she will have to suck his dick and screw him when shes overly tired form working every day, waking up to a hard on? What does she expect ? So its hypocritical she wants to fin work early. Shes 21 What makes matters worse is the fact she couldnt Stand it when my mum over used the word babe to her ex, and now my sister will be talking to mum about her pathetic relationship when I'm in the other room and can hear saying , I said babe..etc etc blah blah blah!! Can u tell me why she carries this on and talks like this when she knows I'm inn the same house and can over hear as I'm hyper aware Is she doing this to piss me off?? And she said I cried again on phone , shes like I have my period too , oh c'mon man she tells my mum this shit to show off the fact she is in a relationship Nd pretends to be "attached " I'm glad lockdown has happened, now see how long they last with out going over there amd having to fuck him! Hahhaa one month no sex for him shame. Then I over hear her talking about his family and how hes all down cause she doesnt want to go over there while lock down Oh BOO FUCKING HOO ..Grow the fuck up