Context:
I met a girl named Anna in a class at my university just under 2 years ago. Only toward the end of the semester, when we were working together as part of a group project, did I start to develop feelings for her. After that semester, we didn't see each other often, but we did connect online and play games together when we had time. Any time that we did hang out was with a couple other mutual friends from the class we had together.
Another semester passes and I was leaving for work in another state (U.S.) until the end of the year. The first couple months I did not have internet access, so Anna wrote me letters (I gave her my address before I left). She wrote me more often than my other friends/family, and on one occasion sent pictures as well. I really appreciated her taking the time to write letters and stay in touch with me, especially since she was about to graduate and had a lot of other things to take care of. It felt like we were making a good connection even though we couldn't even see or speak to each other. Then after the first couple months, I had internet access again, and we regularly stayed in touch online.
The direction of this context implies something: I assumed Anna was single. This assumption was based on what I could see on social media, and the conversations we had (e.g. never once mentioning a boyfriend, no relationship status). I never asked her about it explicitly, since that's not how I typically approach it, unless I feel it is appropriate. In this situation, being away for most of the year, I personally did not feel it appropriate to ask Anna about her relationship status or to ask her out.
Fast forward to the end of last year, I was a month or so away from finishing work and returning home. One day, Anna shared a picture of a guy that I noticed she hangs around with somewhat often, and said that they were going to move in together once they started working. I decided it was a good opportunity to ask if they were dating, and she responded that they were. I also learned that they've been together for 3+ years. It surprised me since I assumed that I would hear about him at least once in the 2 years that I've known her. I've also made my interest in her quite apparent over the course of the year, so keeping her relationship a secret had been giving me the wrong idea.
Once I returned home, I wanted to meet up with Anna, to see her in person and to talk about my feelings. The discussion went very well; we both equally shared our thoughts and reasons on the matter and I felt like I got the closure I needed to move forward and continue being friends with her. From what I gathered, she didn't know how to tell me that she was in a relationship so she decided to keep quiet about it until I asked. Since then we've been enjoying our friendship with no hard feelings.
Currently...
I've been having lunch with Anna the last couple weeks. This is the first time she's wanted to sit down with just me (usually we invite some mutual friends). I learned that she has recently moved out of the place she was sharing with her boyfriend, back home with her family. She only mentioned that she did so to help take care of her injured mother (which I don't doubt). I thought it was a temporary thing, but she said she's no longer going to move back in with her boyfriend.
I think Anna has recently ended her relationship. I noticed that her relationship status on social media has also changed to single, but since then it has become hidden again. She also appears more receptive to activities I've suggested, with just us two.
I have given this a lot of thought, and decided that I'd like to give her another shot. However, I still don't know for sure if she's actually single now, or if she'd be genuinely interested in being in a relationship with me. Furthermore, I understand that if she had ended her relationship recently, it may still be a sensitive idea/subject.
Question: How do I approach her about her relationship status, or learn about it, such that I don't unintentionally offend her or make her feel uncomfortable?
This would be the next important step for me, after which I believe I can explore whether or not she'd be interested in dating me. I just don't want to get my hopes up and repeat the whole previous year all over again.
Note: I've tried to provide sufficient context while cutting out unnecessary bloat. If there's anything that could be improved or clarified, I would be happy to do so.