I've been married a year and a half, started dating almost 5 years ago. He's a cishet man. I discovered who I was and came out after getting married, and we're still very much in love-- possibly even more so now.
It's possible, but even cishet people have a hard time finding lasting relationships too, no? Not to say that nonbinary people shouldn't complain, because it does feel like more of us are single than not, but relationships iz hard all around.