User blog comment:B214/Question and Answers 3/@comment-4547267-20140721005249/@comment-24502975-20140725220825

They're not really stalkers, they just don't want to lose to one another and therefore at that time with Ise and Akeno, they didn't want them to be alone (especially because he wasn't with Rias at the time).

Rossweisse was a different story entirely because she has the best qualities of several of the girls AND is an older woman (in other words a real threat lol).