
I think Aiji and Seiji are not mates like Towa thought, because if they're mates then they wouldn't be able to have sex with Towa like they have been doing, and Seiji wouldn't react to Towa's heat either

Ah, not necessarily. Different Omegaverse stories have different rules. There is no one set of rules that defines them all. In some of them, the alpha can have a bond with an omega and still have sex or even multiple bonds with other people (omegas, betas and other alphas alike). And it would not be far fetched (as some of them do have omegas that do top), to assume that even with a bond, while an omega cannot have someone top them because it will make them sick (and again, in some of the mangas, that only happens if the omega is in heat at the time of sex), that doesn't necessarily mean that the omegas can't top someone else. It all depends on the individual author's choice and the rules geared toward that specific story.
Basically put, YES, the brothers can be a mated bonded pair and still have sex with the Towa, if that is how the author wants to present it in this story. Heck, I even read one where two alphas bit the same omega at the same time, so that they could have a "triple" bond.

The twins are bonded together...
Seiji the ALPHA can have sex with other people and can have multiple mates
But Aiji the OMEGA cannot have sex as the bottom other than with Seiji (I presume he can only TOP others but CANNOT BOTTOM to others cause it will produce unwanted symptoms)
Aiji can have sex with Towa cause he is the TOP and he only BOTTOM to Seiji...

I kinda dislike the uke at this point. It feels like he blames the seme for everything

people always use 'tsundere' to fit their own agenda. if he acts like an ass hes not a tsundere, hes just an ass, if he doesnt like the seme hes not a tsundere, he just doesnt like the seme. why people always gotta use 'hes a tsundere' as an excuse? smh. if hes an ass now, but isnt one later, DOESNT mean hes a tsundere. man i hate that word.

disgusting
disgusting
disgusting
I literally cried when I read this chapter. I used to wish for Ikuro to be together with Norihiko, but now, somebody please KILL THAT FUCKING OLD MAN NORIHIKO!
He hid the fact about the other company from Ikuro to trap him in this shit!!!!
Please, just kill Norihiko, and let Iida heal Ikuro's soul. Please....

Hey hey people, Iro doesn't know that Rene's not gonna come home for 5 days! The secretary didn't tell him!
To Iro, it's just like normal days when Rene goes to work then come back in the evening, and of course the cat can wait like it always does before Iro comes.
It's not his fault that he left the cat since he doesn't know!
AND I think the other guy will come and take care of the cat (or kill it, which I never want to happen, because it's from Rene's unrequited love). I hope the cat's alright.

"fall in and out of love"? Does that mean some of the couples actually break up or something? Does the manhwa involve any cheating? Please tell me, thanks!

Well this is composed of different stories( so far there are 4) , so you can skip the second, I personally didn't like it, but it didn't really ended heartbreaking, but still meh ( I don't want to spoil it for you)... other stories are very good! Especially 1st and now 4th, so I recommend you to read it! (●'◡'●)ノ
IF YOU SLEPT WITH THAT BITCH THEN DON'T EVER LOOK FOR IRO AGAIN!!!
RENE AND THAT SLUTTY EX SHOULD JUST GO DIE TOGETHER IF THEY WANT TO TALK ABOUT SUICIDE THAT MUCH!
Okay, if you're so scared of that guy's committing suicide that you slept with him, it must mean that you decided to be together with him from now on right? The "if you leave me I'll just die" can't be solved with just one night of sex.
THEN WHY TF DO YOU STILL GO FIND IRO????
This story just went from fluff and potential romance to dirt real quick.
EXACTLLLLLYYY