User blog comment:B214/Volume 17 spoilers./@comment-24588585-20140225001025/@comment-95.252.52.167-20140225215141

Another girlfriend? He has Rias ("legal girlfriend"), Rossweisse and Koneko (she proposed to Issei and he said that he will be happy to do it if her body and her chest grown up, and with senjutsu we saw how will be Koneko's body in the future, so it's technically a "yes".)XD