My(24F) sister’s(19F) friend(20M) likes her and makes her uncomfortable and she doesn’t know how to reject him without being rude.

So my(24f) little sister’s(19f) friend(20m) likes her and he makes her uncomfortable. She came to me for advice but since I also struggle with being too nice and setting boundaries with people, I don’t know what advice to give her so I came here for help. She said they have been friends for years since high-school but recently he’s been inviting her to hang out one on one without the group of friends that they share. She agreed to see him at first one on one about a couple of times thinking that it was just a friend outing.

But he has been invading her personal space and touching her arm or her knee during conversation. He also liked to take photos with just the two of them while they were hanging out with the group of friends (and alone) where he put his arms around her. She has already talked to him about this but she made up a lie to him about why she doesn’t like hugs or being touched like that and he has stopped. She said it was because of trauma. Which isn’t a total lie, but it’s also not the whole truth since she told me that she wouldn’t mind a casual hug from any other friend but she doesn’t want to give him mixed signals.

There came a point where he would text her and call her constantly and would keep her on the phone for hours even though she would say she had to go from the call soon but he would keep talking and talking and talking while supposedly saying goodbye before hanging up the phone. At the time that he would invade her personal space and talk to her on the phone for hours, she had a boyfriend and thought that it wasn’t really appropriate but she chalked it up to his lack of social awareness/social understanding. But still, she didn’t want to seem like a bad friend. After she broke up with her boyfriend, the friend talked to the group, she heard that he was insinuating that there was something going on between the two although he never outright said it. This left a bad taste in her mouth since she didn’t see it like that.

She had also thought she made it clear to him that they were just friends when on the phone with him one day, he told her that his parents thought that she liked him (when hanging out one on one, his parents were their ride because they both don’t drive yet) and he asked her what she thought about that and she said she only thought of him as a friend.

He kept texting and calling her and she suspected that he was still pursuing her.
Once he asked her to hang out one on one again and she said no because she was broke so he wanted to pay for her. If it was a regular friend she wouldn’t mind but because of the past with this particular friend, she said no because she didn’t want to give him any ideas. She didn’t want to reject him in a rude manner so she decided to slowly create space between him and her. But this also meant she would have to create space with the group of friends they shared.
She also doesn’t want to create any drama in the group and wants to just kinda “fade” away from them instead of leaving on a bad note. She started not showing up to group hang outs and she stopped texting the group saying she was going away for a while to find herself or something like that. Which also wasn’t a lie but it also wasn’t the whole truth. He kept texting though and calling her. (She would not pick up the calls but she would text him back because she didn’t want to be rude) and she would explain that she was still on her healing journey. He would ask her when she thought she would “come back” from her healing journey and she said she didn’t know, whenever she thought she was healed but that it’s not something she could put a schedule on. He seemed to understand but he still reached out to her and this seemed to her that he was not understanding her. She doesn’t want to be rude and she thinks that slowly making distance from the group and him little by little is the best step and it’s been about a year since she has started doing this distance thing but he still tries to text her.
He keeps asking her when she is coming back and wanting to make conversation to her through text and sending multiple 15 minute long voice messages to her and she keeps explaining that she can’t really talk right now because it’s part of her going into “hermit healing mode”. He responded that to heal she can’t be in hermit mode and to try coming out of it again. To this, she has told him that she thinks it’s the best route for her to take.

Also, she has posted on her story about her going to the beach or doing something else and although, there was no one in the pictures besides her, he dms her asking her who she went with and what about her “hermit healing journey” which she has responded that she went with her sister (me, which was the truth) and that she still hangs out with her family in her healing journey.

She decided to finally come to me for advice because about a few days ago, he texted her again saying he really needed someone to talk on the phone with and before, she would accept, and he would vent to her about his problems for hours on end. She has not answered this last text message though because she doesn’t know how to reject that idea without seeming rude. (Any ideas reddit?) She is kind of tired of it all and doesn’t know what to do now without him labeling her as a bad friend to the rest of the group. And she also sometimes thinks she is a bad friend.. They don’t know everything she has told me about him and she wants to keep it that way but doesnt want to leave on a bad note.

TL;DR
My sister’s friend keeps bothering her because he likes her and although, she has sent clear signs of her romantic un-interest in him, he keeps texting her and calling her.
She made a plan to slowly distance from him and their friend group but he is still very adamant on wanting to text, call, and hang out with her. She doesn’t want to leave the group on a bad note or create drama so she is being passive about it.
Advice?