@Fuko
it's still too early to make any accurate predictions.
I've just thought of 4 possibilities now:
1. it's not confirmed that she doesn't remember him, she may have said that to test him to see if he has his future memories
2. she was standing a a bit farther away from the group when the explosion happened, so whatever caused him to time travel way have affected her differently: i.e. she travels to another point in time
3. MC supposedly has the most magical talent out of the group, so maybe he instinctively protected himself with his magic or something.
4. the dragon 's heart instinctively felt something different for MC (curiosity/love/fear/rage) because he was a greater threat than the rest of the group. so it's affected him differently (time travel) than the rest of the group (no time travel)