wtf am I dumb cuz I didn’t understand what’s happening like are they both not seeing e...

They're still seeing each other. Because of haeso's outside influences (Mincheol cheating with a younger woman, her boss' reputation), she became uncomfortable with the age gap between them again. Because of that, she asked taeha to keep their relationship very private even though that's not what he wanted. Taeha then had to go on a month-long trip, and is "trying" to stay vague about her existence despite that woman pretty much harassing him.