spoilers
Sorry but I feel like this is slander on Hari's character. If Taemu has a legitimate reason to say it, then Hari has a legitimate reason to not say it too.
when you say "she can say anything she wants in front of others", who are you referring to? The only people she openly talked to about her feelings and her relationship with Taemu was her close friend.
I think you should try looking at it from Hari's perspective a little. Right now I feel like you're only concerned about Taemu and his perspective. If you look back to the beginning, Taemu was setting himself up for this. He initiated the relationship with a particular goal in mind. He was pushing for marriage without even considering its importance. when he pushed for it again when all Hari wanted was to start dating for real, of course she will be suspicious and anxious. She wasn't selfish, she was being cautious, cautious of Taemu's true intentions and feelings. She had always wanted to get serious with Taemu but she denied him that goal because she still wasn't sure if Taemu wanted her for her, not just a marriage for the sake of it. Her being "uncomfortable" was her realizing she didn't need to be cautious anymore because their feelings match, so she finally gave in and told him yes.
Taemu truly loving Hari and wanting to truly marry her does not negate her insecurity, he can have all the reason he wants in the world to expose their relationship, but if Hari is still cautious about his intentions from her own interpretation and deduction, then he simply can't do that. If he does, it will confirm in her eyes, his intentions that he only wanted marriage, not her. So after reading all that and you calling her selfish means you didn't understand her as a character.
If you still insist she is selfish then Taemu is also selfish, in that he wants to marry her when he doesn't even understand her insecurity. If he caught himself, he would have known pushing for marriage is just a repeat of his earlier self, even if his true feelings have changed since then.
By the end of chapter 81, I realized how selfish Ha-Ri was. She can say anything she wants in front of others, but Taemu has to wait for her approuval and stay quiet even when he is feeling insecure. Once she feels slightly uncomfortable she decides to expose their relationship, but lets her boyfriend feel anxious even tho he is the one who has a legitimate reason to say it!