Please help me recall the title of this manga

it's an omegaverse. The omega is from a poir family with lotsa siblings. The seme is yiur typical cool, handsome rich kid. Thehgo to the same school. One day, while in the library, the uke went into heat. The seme got affected but got a hold of himself and didn't bite him. However, they ended up being boyfriends but thy're not yet a pair. Then the uke thought he was pregnant but it was false alarm, they went to the seme's flat and the seme made the uke wear a wedding gown.