Help me find this manga!

So this is what I'm remembering from it:
The crown princess to be having tea with some friend and they worried, because same rumours from CP and some girls, crown princess-to-be didn't give a crap she trusting CP completly because they going to rule the country together. Later the girl confornt with her like "we like each other so break up the engagment etc." but CP is like "what when did I said this? I went with you these places because if I go with my wife-to-be it becoming an ispection" , thus girls delusion got crushed.
The there is the second couple the lady is friend (?) with crown princess-to-be and watching their trust in each other and their relatinship, she deciding that it's time to do something with her own fiance. Her fiance marasquis or duke heir, but he completly negleting her and his duties too, because of that (commoner?) girl. The fiance usually sending his lil bro to do his work, be his proxy, take fiance to balls etc, so she deciding make lil bro the heir and her fiance because he is more suitable and reliable