It's not just about that inwoo can't taste food but it's bc he cannot show any kinds of enthusiasm towards good food and even tends to be disgusted with it. Not only that but he also carries a lot of emotional baggage (his trauma) which was just too much to handle for his ex-wife. She also loved eating yummy food but couldn't do so with inwoo and even if they did her joy would quickly be ruined by most likely inwoo's insensitive comments. With romance partners it's less about eating really good food but both of the partners enjoying it together. There's also the saying that Love goes through the stomach. Sharing meals together atleast once a day strengthens family and partnership bonds, so if the enjoyment of eating meals together is only one sided the whole time, or just not there at all, then it can lead to loneliness and them growing apart. It was also mentioned that the ex-wife was dependant on alcohol while they were together, which is obviously not healthy, physically nor mentally. On top of that inwoo was also dealing with his trauma, unable to get better at all, which of course added stress to both of them and yes, that's why at some point his ex-wife couldn't take it anymore and they decided to divorce. To be fair that was the best choice for both of them at that time. (Basically: it's not about indoor being unable to taste food, but about the unavailable emotional bonding)
Why did the male lead wife leave him? It can’t be just because he can’t taste food like that’s so stupid. It’s not his fault. Who leaves someone just cause they can’t taste food.