Should a relationship that is strong enough and long enough be able to work through infidelity Disagreement with boyfriend?

So recently, a friend of mine and her boyfriend broke up after 7 years because she made a mistake one night while he was out of town for work and slept with another guy, and although she confessed, and was sorry, her boyfriend broke up with her immediately.

I told my boyfriend of 3 years about it, and he said "good for him!" and I asked him what he meant by that and he said "there's no taking back a cheater" and I said "even after seven years?" and he says "I wouldn't care if it was 70 years, cheating is an instant dump".

We argued back and forth, and I said it makes me doubt our relationship if he could dump me instantly for cheating, and he said "it's simple, don't cheat" and I said that sometimes, things happen, people make mistakes, and we argued more and now we aren't speaking to each other.

I think his view is too black and white, but he refuses to back down or listen. I believe a strong, long term relationship should be able to work through anything.

Thoughts?

Oh, and don't waste time just telling me what a horrible person I am, please answer the actual question.

Should a relationship that is strong enough and long enough be able to work through infidelity Disagreement with boyfriend?
Post Opinion