Try some edge methods to solve it first. Is to make the smell disappear, leaving no trace. For example, girls usually care about their leg shape. You can tell her that you have a good idea, that is, soak your feet with hot water every day and add some medicinal materials to it, which can not only promote blood circulation, but also make your calves lose weight unconsciously, and keep healthy and prevent diseases! If you use this method, she will be willing to soak her feet. You'd better get together again and urge her every day. I believe that under this method, the problem of her smelly feet can be solved within one month, and the problem can be solved from the root without hurting anyone's heart.
When I was in college, there was such a girl in my dormitory. I used this method after consulting with another girl who has a good relationship. Everyone sits together for foot bath therapy every night, which not only enhances emotional communication, but also solves the problem in a harmonious and low-key way.
If she doesn't want to do it with you, there is really no better way. Can only say, but can be euphemistic. After all, everyone has a strong self-esteem. You can say, Oh, it's too hot, and our feet stink! In this way, you not only tell the truth, but also protect a girl's heart, and then take her to wash her feet together, and it will be solved.