Whether she is dating someone else or not, in her mind there is nothing wrong with that 1) you’re not together, so it’s not like she’d cheating on you and 2) since she informed you she’s dating again/going out on dates she feels she’s being honest and open with you.
I came into his life at a very trying time and I lifted his spirits, put him in a better place and kept him on track. He was looking for something negative that would help him to make his decision but he couldn't find anything.
Just think of it this way: you've done no harm by trying. Continue to remind her that you want to date her, you don't just want to be her friend (that is, you don't want to wait in the wings).
But if she's interested, and her relationship is on the rocks, she might get in touch after they break. Just because she's in a relationship doesn't mean you can't make your romantic intentions clear, or else you might become the brotherly shoulder she cries on whenever there's trouble in paradise.
The tips and suggestions in this guide will help you to find out if she has a boyfriend, without being too direct, or making either of you uncomfortable.
My question is: Can I ask my ex if she is seeing someone else and if she is, what do I do?