[EnigmaticAxiom]

Originally Posted by rejer

TBH I really think like this. And I think I'm not the only one.

Just reading 2ch thread made my mind all blurred.
They were going on and on about Shizuku(?), Erika, etc, and I was like what is going on with all these girls? (like this one)

Spoiler for My take:

Mikihiko and Mizuki clearly like each other, but nothing has been done by either of them to advance the relationship

Erika and Leo are always together, and the group teases them occasionally, but there currently are no visible romantic emotions. It's more along the lines of them always being around each other. They are extremely touchy when their friends tease them about doing things together

Honoka likes Tatsuya romantically, no doubt
Ayako (the second cousin) likes Tatsuya romantically, but nothing concrete has been shown between the two, and I believe she is like the other Yotsuba family members and distances herself from those emotions
Miyuki likes Tatsuya romantically, but she is still more towards the sibling love aspect as of now (despite her numerous advances, I still believe this is most likely since she worries about the time when she will love him romantically more than as a sibling).
Mayumi likes Tatsuya, though it is up for debate as to whether she truly likes him romantically. I believe she is similar to Miyuki in that she likes him as something of a sibling. Rather than saying she likes him romantically, I would say she is currently conscious of him.
Lina I would have to say likes Tatsuya romantically, but she is denying it. Arc 6 specifically states she experiences a suspension bridge effect (developing romantic feelings when one confuses a dangerous situation for romance), and she made him chocolates for valentines day (though she did not give them to him). I think she's more confused about her feelings than anyone else.
Shizuku shows no signs of having any romantic feelings for him.

Tatsuya himself is ignorant of all these feelings save for Honoka's. While Miyuki is always making open advances on him, he is always worrying about her awareness as a girl and brushing her off, though he does feel uncomfortable due to her advances at times.

Given the short stories and how the author writes, Miyuki and Mayumi are likely the top two choices. Honoka and Lina did not really get much play until the last two arcs, though, so they may start playing a large role in the romance sub-plot starting in the second year.