What are the red lines in terms of relationships between Officers and Officer Candidates?

I don’t think it’s right whatsoever. But it’s happening in the same COC and is toxic. The Officer Candidate in the relationship doesn’t have to do anything and can miss whenever he/she wants and gets away with. (Not to mention he/she shows up and leaves whenever he/she wants for work when on ADOS and gets awards for nothing)

Also, I don’t know what to do. I brought it up with Cadre and they said it’s not hurting anything and told me keep on the DL so no one finds out. They also said the Officer isn’t considered cadre so the Army is okay with it lol. I thought about bringing it up to the Battalion staff’s attention like the Major or LTC

You need to skip your COC than and utilize whatever open door policy you can. Don't worry about upsetting him/her they wont be your COC much longer. Its not just making your experience unfair, but an officer candidate will eventually become an officer and if they were playing hide the salami during something important it could get people killed. If your COC wont do anything about it go to the IG. Also to be clear, are we talking about commissioned officers or cadre acting as officers or cadets or what?

If its anything like enlisted basic the cadre are often times holdovers who are awaiting assignment and don't know dick about the military and how it works. The Army is never ok with anyone in a direct COC having a romantic relationship with a subordinate. Again this is double the case when it comes to TRADOC.

You ask that like I’m interested or everyone knows that. But it’s happening in my unit and it’s still going on