An Abandoned Secret Lover

I went to pick up my older brother who was out at a gathering. That was when I overheard him ask Nathan, "Haven't you been dating someone? It's been so long, and I still haven't met her." I suddenly tensed up. Nathan and I had been together for three years, but we had always kept it a secret, so no one knew. Nathan replied lazily, "She's not my girlfriend, just a pastime. It's not like I plan to marry her." I clenched my fists and pushed the door open without hesitation.