OUUHH good question.. i think he overcompensates at first, like tries extra hard to be a good partner and puts in maybe a bit too much effort and its painfully obvious. so sungho sits him down and is like... you can chill out you know you don't have to do all this. and taesan tries to argue that he's trying to make up for lost time and his mistakes and sungho tells him it's fine, they have plenty of time together and he doesn't have to, which helps him relax a bit.

and like i said in a previous question taesan starts going to therapy YAYYY so he has a good outside outlet for his feelings where he can voice his worries and anxieties without feeling like he's burdening the people he's close to. it's awkward and scary at first but he sticks to it and it helps.

he also tries to be more open with sungho, so whenever he starts feeling that anxiety that he doesn't deserve this and shouldn't be allowed to be happy, he'll tell sungho instead of keeping it locked up until it boils over, even if it's hard, and sungho will quiet him and reassure him and they'll take the time to do something together, especially after they move in together.