ughh this shit is hard man, I feel like it might be the 3rd option but how do i know for sure
Well one thing you can do is ask her. If you want a healthy relationship, communication and trust are key elements. It sounds like trust is already a bit strained (but that's kind of okay, you're still getting to know each other). So if you also have communication issues, then I wouldn't expect this relationship to last particularly long. But honestly, if she's the kind of person who wants you to "front" for her... do you want to be with that type of person? I guess it's personal preference, but I wouldn't want to have to deal with that stuff. What I would ask is:
"Are these guys bothering you?" followed by "Would you like for me to talk to them?" If she says yes that's already kind of a red flag, but you could then say "Okay so let's brainstorm the objective here and just double check if this is the best way to achieve that objective."
In contrast to most of the other comments above, I can kind of get her response to the guys so far. She's reported it to HR, but the guys are still skirting the edge of respectability. No one wants to be hated by their co-workers, and these are people she has to pass a lot of time with. It's not fair, but if she outright goes nuclear on them, she might have to suffer a lot of micro-aggressions or passive-aggressive bullshit, none of which are individually bad enough for HR to take action. Especially if the workforce is mostly male. Plus she might lose out on free rides.
So instead she has to keep "friendly" even though she might have no desire to actually be friends. The guys know this and will play in that quasi-flirty zone. If this is the situation, you getting involved only makes things worse. Now they know you're insecure and can use that to their advantage, try goading you into doing something stupid or adding strain to the relationship. Once they add enough strain to the relationship, maybe she'll dump you or want to cheat, or whatever. I'm not saying this is what would happen, but rather trying to guess at how they might think.
The biggest risk is not "Oh no these guys are texting her and bothering her but eventually wear her down" because those guys are almost certainly annoying. The risk is that there is someone she enjoys talking to at work and enjoys texting with, etc. Going down to HR / going down to confront them does nothing to help with that. Even asking her to stop texting guys is not going to help with that.
The best way to address that risk is to make time with her, get to know her, see if you're actually compatible, communicate, etc. If she dumps you after 3 months because she's bored, then you are much better off / you two just weren't a good fit.
