Matthew does not complain about his first time. It was customary, tradition, a lesson straight from the textbook, as all Nations' first times are. But Matthew was young, too young to understand what was going on, and that has scarred him.
He no longer blames France, even though it is his fault. "Zis is a hard lesson to learn, Chère, especially for someone as young as you," Matthew distinctly remembers him saying, his voice soft and his eyes downcast. He remembers the concern that he felt for his Papa and the joy that overcame him when he learned that the war was coming to an end, as well as the betrayal that shook him to his very core when he was told that he would have to move in with England. "It may be difficult – it may be impossible – to trust me afterwards, but you must promise me zat you will at least try. You must remember that you are mon petite Chère, and I would never purposely try to hurt you." And despite the burning hurt and anger in his gut, Matthew believed him. Even now, he believes those words, because unfortunately, Matthew is a forgiving and trusting person. He's had his heart broken one too many times, yet he's still eager to put faith in the world where faith is not due.
So when Gilbert said that he loved him, Matthew believed it because he wanted to, not because he thought it was true. I love you; I would never hurt you on purpose; just trust me: Three different phrases he has heard from three different people but he wants to believe that this time is different. Ich liebe dich, Matthias and Je t'aime, Jilbert and that's all he can ask for.
But Gilbert doesn't know about Matthew's first time. He doesn't know about his fears and phobias. He doesn't know about his masks. Matthew is layered, perhaps more than any other Nation, and that translates into social awkwardness, which is all Gilbert understands because that's the only version of Matthew he ever sees.
Neither of them ask for sex because they've both had awkward encounters, but inevitably, the day comes when Gilbert wants to try, and Matthew says no for one reason alone: He knows that Gilbert won't let himself be topped. Well, neither will he, which leads to an argument and a terrible, terrible misunderstanding.
Gilbert means well, he really does, but it's a serious case of I Know What I Want To Say; I Just Can't Say It Properly. And Matthew is in pain; he is burning everywhere: His skin burns where Gilbert touches him; his eyes burn with withheld tears; his soul is on fire with a love he knows is not love and a betrayal he knows too well. And when finally, finally, it is over, he is still burning, and he feels like it will never stop. He feels like he is to be tortured forever, no matter whether he decides to trust and forgive or to hold a bitter grudge against everyone and everything. He is the world's scapegoat no matter what he does or how he behaves.
But he knows that Gilbert really does care for him, and that just makes the pain worse, so he gets dressed and leaves, and he drives and drives and drives until the car quits on him in the middle of a rainstorm. He is rescued (after an eternity of sitting in the driver's seat, pitying himself) by a Nation far too familiar for comfort. But when Gilbert stops by, looking for Matthew, his saviour lies and promises to keep an eye out for him, to which Gilbert replies, "If you see him, can you tell him that I'm sorry and that we need to talk?"
Maybe he really does love Matthew, but the Canadian is far too broken to take comfort in that.