2 easy options...
1 - Make the roof ridge edge Vertical (using pet palette)
2 - Stretch the ridges away from where they currently are, select one roof and CMD-click on the edge of the other - this extends the 2nd roof to where the two meet and gives the edge the appropriate meeting angle. Then select the 2nd roof and CMD-click the edge of the first (especially relevant if the two roofs are different slopes, but works if they are identical too). This can be done to correctly align ridges, valleys, hips or any junction between two roof planes.