Your business is not that "solid" in the eyes of the embassy.
It's more or less "small business" or "one man show". You have no staff on payroll to care for.
If you worked for a established company, you might have higher chance, comparing the situation.
Secondly, I guess both you and your wife are "too young", chance is : they think you two
might seek opportunity to overstay. You don't have kids who have to be in school.
So you two are "more flexible" to move around in their opinion.
----> แต่ความผูกพันธ์ยังไม่เพียงพอ
Just my guess, though. Don't take it personally.
If it were like my comments, you could find ways to convince them in the next round.