Rochelle is definitely at fault too. She's really insecure about the whole partners thing and that Keith isn't with her.
But at the same time, I also think Mandana is kinda unflexible? Keith seems like such an easy going guy and seems to go along with what Mandana wants but Mandana doesn't? Like today, he got annoyed that she constantly didn't let anyone interrupt her. I understood her reasoning (she wasn't finished making her point) but at the same time, she should also understand that sometimes interruptions are natural and constantly telling someone to shut up and listen to you is annoying.
In general, I think the two women are at fault here. Rochelle is insecure and Mandana is self-absorbed.
But yeah, I think Keith's actually been doing a pretty good balancing act between the two so far.