Trenches

English is not my mother tongue, so it is possible that I misinterpret this song. But I think it is about leaving someone whom you still love. The whole first part is about a couple which has created a status quo. They love each other but their live's stagnation.

And although his feelings for her are pure he decided to go. "If I don't make it out, remember the things we had" means that, if she's disappointed and sad, she should think about the good moments/time they had.