That's an emo fantasy. In real life love is not enough. In a relationship you have to grow and change together. You have to make things work as adults. You can't just say "oh we're broken lest stay like this forever" you have to try to fix what is wrong. They can love each other and still move on. Ian knows they are bad for each other that's why he's trying to put distance. Life is about change, things that don't change die.