Whoa, I didn't think Sagara would be one to try to get a reaction out of Aoi but at the same time that does make more sense why all of a sudden there was a woman. And Sagara doesn't seem like the type for a late night stand, especially if he's been in love with Aoi for 13 yrs. It's a bit of a bold move for Sagara if it resulted to either setting back on their relationship or moving forward.
Yea definitely bold of him but even if it did set back sagara won't back down he knows aoi has nowhere to go and rely on except for him so he basically put him in a situation where aoi has to reflect on what he actually feels and what he should do with his feelings with his brother. Also I don't think his in love with his brother anymore its more of guilt for what he did and he missed the closeness they had with each other before.
I agree with you about the "why would he have sex with a random woman while he could do that with the one he's in love with"
It makes sense because Aoi's always at home, so if he wants sex he can always do it with Aoi. Moreover, he knows that Aoi might be home, why take a woman home and make it awkward? He can always do it with anyone in another place instead of making Aoi hear them moan.
Still, if there's nothing between then and he knows Aoi's outside, he should have gone out and taken Aoi home even when the woman's there.
And when they became lovers, he still didn't explain anything :(
I think the author should do something more to make this issue clear.
Well I reread this manga I was pissed the first time I read it cause he slept with a woman then I read it again then I thought maybe he did it on purpose I mean Sagara did say hell make aois favorite food when he gets back but didn't say hell invite a woman and when aoi went home and saw the woman's shoe he got upset meaning its not something Sagara usually does and why invite a woman when you can have sex with the person ur actually in love with even if its not reciprocated its still better than casual sex with an acquitance I guess sugara got upset with the whole mind ur own business policy argument they had so he's taking action by trying to get a reaction from aoi which he did get and it was the ice breaker for the growth in their relationship and judging from sugaras personality he's not the type to casually sleep with someone I mean 13 year he was waiting and not letting go I just feel the woman is just an acquaintance who stayed over. That's just my analysis though since it was not clearly stated by sugara its up to the readers to decide if he slept with her or not.
Oh and I would just add as well that when aoi arrived and saw the woman's shoe sugara shouted out if aoi was there meaning he's not trying to hide her in the first place I don't think sugara is that heartless to sleep with someone knowing your mentally/emotionally unstable sexual partner who your in love with is in the same place.