We understand that this is a controversial topic and is definately NOT part of our headcanon universe. However, we love to explore the nuances of BTS’ personalities and characters and this is more of a what if scenario. Not meant to offend anyone.
We feel that Jimin is the most likely to cheat on his partner under the pretense that he was not aware that they were “exclusive”. We feel this mostly comes from his insecurities and his desire to be accepted and loved. You can often see this side of him in interviews and behind the scenes clips, where he relies heavily on the other members and is constantly seeking their approval. We do think, generally speaking, Jimin would be a good boyfriend, but we see many of his relationships at the moment being short term flings which do not last because he is not yet ready to commit to just one person. He might end up seeking someone else if his girlfriend was not giving him the kind of attention he craves. He would feel guilty afterwards but would avoid confrontation at all costs, not telling his girlfriend he cheated.
While Jungkook would never deliberately want to hurt his girlfriend or set out to cheat, he would be the most likely to get carried away with himself in the moment if another woman came onto him very strongly. (We feel this kind of regretful moment is best shown in our “7 Minutes of Heaven fic). When it comes to having self control around women, we feel Jungkook often fails, particularly if the women is older and has large breasts. He would never ever make the first move or deliberately flirt with someone else, but if he found himself cornered by someone, he would be unable to stop himself from kissing her back or taking things further. He would feel absolutely horrified with himself afterwards and the guilt would follow him around constantly; giving him away to his current girlfriend who would notice the stark change in behaviour. If confronted about it, he would break down and reveal everything, explaining how powerless he felt. His girlfriend would likely end up feeling very conflicted, on the one hand feeling hurt and betrayed by him (”you didn’t have to stick your cock in her though, did you?”) but also feeling sorry for him at how terrible and broken he feels.
We feel that Taehyung might either cheat if he was in a particularly destructive place personally, and his current relationship was almost over anyway, or if, like Jimin, he didn’t realise you were exclusive. Taehyung would often he aloof when it comes to new relationships and might genuinely not realise that you were exclusive when you first started going out, particularly as he would be slow to reveal his feelings and this might cause you to behave in the same way. If he felt his relationship was falling apart, he might end up getting a little too drunk and silly and having sex with someone else, meeting them at a club or party.
We feel that Namjoon would be, at the worst, capable of passionately kissing somebody else if he had gotten into a particularly heated argument with his girlfriend. We feel he often gets himself worked up and jealous to an extreme extent and might go out of his way if he was in a foul mood, seeking to cheat on his girlfriend as revenge. He would never be able to bring himself to take things further than a kiss though, immediately feeling guilty. If he felt he had inadvertently led the other girl on too, by getting her worked up with a passionate kiss, he would feel double the amount of guilt and would end up going home with his tail between his legs.
With Yoongi, we feel it is extremely unlikely that he would ever cheat on his partner. However, like Namjoon, he is capable of getting himself very worked up following arguments. He is one of the more fragile members of the group and definately has an emotionally masochistic streak. He would only ever cheat if he felt the relationship was over anyway, almost as a way of torturing himself further. He would not want to kiss someone else or be too intimate with them, but just want a quick release. He would likely let someone give him a handjob or blowjob but not go all the way with them. He would feel terrible afterwards and be very hard on himself for weeks following the incident. It would be the breakup with his girlfriend itself, though, which causes him more pain in the long run as, despite common opinion, he would take relationships very seriously.
We do not feel that Hoseok would ever cheat on his girlfriend but may cause her some distress by dancing too “intimately” with someone else. Hoseok is naturally a very sensual person, particularly when it comes to how he moves his body, and wouldn’t realise how sexual it was coming off. If his girlfriend brought it up, he would feel bad that she was upset but also quite baffled as he genuinely would not have realised how it looked.
We feel that Jin would never cheat on his girlfriend, even if the relationship was virtually over or if someone came onto him. The worst case scenario would be if another girl kissed him without his permission. He would gently pull her away and explain that he had a girlfriend and was not interested.