Hmm.... Cleo's stuff....
1) in her heart, in her life, in her home..... Could be either Elaine or Monica, but I'm betting Monica.
2) sisters: sweetness there, but not all sweetness is natural... Could indicate Katie (her sweetness took work, also a lower point will be where I theorize she's adopted... There's a hint in episode 21 and she does not share features with Monica or MC (Note, I also theorize Monica is MCs Mom and Jenna is MC's blood related sister, I did NOT pursue Monica sexually and she found out about MC and Katie's relationship and didn't freak further adding a bit of support for adopted Katie. Also, on a bad path, Monica DOES lose her shit about Jenna) It could also indicate Elaine and Bella supported by my point 3.
3) The sister introduces a pretty blonde, she is close to you but closer to the sister. I'm theorizing Jenna and Joline and that Joline is bisexual with slightly more lesbian tendencies. It could also fit Katie and Debbie, but this really doesn't fit as a) if my above "adopted" theory is correct then Katie cannot be "the sister" and b) Debbie is into Lily, not Katie. Also, it could be Bella, she is another "sister" and she's acting all suspicious, but as I recall, she didn't introduce you to any blondes, did she???
4) The blonde likes you but prefers women. This further (IMO) supports my Joline theory, Joline ALMOST confessed "something" in the 3some with MC/Joline/Jenna.
5) The sister and her blonde, a will, a key, and a house beside the sea. This is an obvious reference to the beach house, but is it TOO obvious? Could it be anecdotal? The will, could be the physical will or could it be the will to push through and find happiness? The key, there was a (IMO) too obvious reference to the key under the rock of the beach house. Could also be the will to find the key to finding happiness. So, theoretically, Jenna and Joline and MC find the will to muddle through and find happiness in the house beside the sea (IE: screw the money, end up in a Jenna centric throuple) Note: I don't think that's likely, I think there will be SOME way to have it all! (except my MC doesn't deserve shit, cause he's a cheating, lying bastard whose only redeeming grace is he DOES really like/love all his LIs
)
Further points, the Lawyer hints dropped, I don't remember all of them, but his last comment, home is where the heart is seems particualrly relevant. MC sort of has three potential homes. Monica's, Elaine's, Beach House. Any of them could be where his heart is depending on how it works out.
Just my thoughts so far, almost to the end of 21.