This is hilarious, they really went there. 'Let's keep our relationship a secret!', also 'Let's talk about love while on a date for national TV lol'.
Also, the advice from Tetsuo's sisters was good but it made me think that the manga didn't even aknowledge that Tabata's social standing should be pretty high already. She's the close friend of Uguisudani and Otsuka, she's part of the greater friend group with the popular Ueno. No one in their right mind would talk badly about her because it would burn any relationship with Uguisudani and Ueno, and potentially invite a shit storm if they were the kind to start a smear campaign in retaliation.
Tabata's low self-esteem is one thing, but if you want to have teenage bullshit be a little accurate, you can't ignore facts like that and still treat her like if she was an invisible outcast. Well, actually I've seen once what I find the proper reaction to Tabata, when some girls were curious about her when she showed she was close to Ueno and Ugui when doing introductions, and another time before that, but then it was never addressed again.
Well, I'm going to see now how it will be resolved but the only thing to do is hold your head high and tell off anyone foolish and rude enough to say anything.