How to detach from an online friend ?

How to detach from an online friend ?

Alright I'll keep this as short as possible. So I(22) was going through a treatment and was feeling pretty low and one day I just randomly commented on a post regarding that treatment. And then that person whose post I commented texted me and then we had a chat. Since we both were going through the same treatment and we both we mentally exhausted, we connected pretty well. And earlier we used to talk daily and this continued for months and I seriously thought that damn I finally found a good friend but then she started to reply late and all also was dry texting so I was like ok fine she doesn't wanna talk anymore it's fine but then again she started talking normally. And whenever she replied late like 3-4 days later she would say that she wasn't feeling well. So I didn't mind. But this just keep happening again and again. She is older than me (3yrs) so there's no romantic feeling involved too. It's just I like to talk to her. Lmaoo does it even makes sense. It's mentally exhausting. I feel like it would have been better if I hadn't commented on her post.

tl;dr: Bonded platonically with someone online during a tough medical phase. We talked daily for months, but now her replies are very inconsistent. The on-off communication is mentally exhausting, and I’m struggling with whether to keep the connection or let it fade.