First of all, timing (such as eating at night) doesn't affect weight loss. Some people like to stop eating at a certain time because if they don't they are prone to bingeing. But simply eating after a certain period of time worries you, there are tons of studies out there that demonstrate timing of meals has nothing to do with weight loss. It's one of those pesky little myths that won't seem to go away
Regarding dessert after dinner... I come at it from a different point of view. I used to look at desserts and sweets as something I earned, a reward, a treat. I thought, like you, I HAD to have a sweet after dinner- it was non-negotiable!
I moved from sugar-based desserts to artificial ones (sugar free jello, etc). But that only reduced the calories, it didn't change the association I had with "deserving" desserts and "needing" something sweet. Advice that someone else on 3FC once said is "question all your assumptions. EVERY one of them." This has helped me change habits and behaviors I always thought I had to work around.... first it was lowering my carbs and cutting out bread, then it was reducing processed sugar... etc. I have really worked hard lately at not eating a sweet after dinner. I don't "deserve" dessert- I deserve amazingly healthy and tasty nutritious foods!
I have nothing wrong with dessert- I definitely have it every now and then when I want it, and I have more of it on special occasions- birthdays, holidays, etc. And sometimes I do crave it after dinner. But breaking the association I had built up between after-dinner relaxing and dessert has been huge in reframing my whole attitude towards sweets.
Just a thought. Good luck!