This is long, sorry. It's the type of fan I am. However, I think it makes my point.
ttp://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-9/14/
Kotaro calls, then sends Ayumi a message. There is no call back or reply message, followed by a montage of daily life.
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-9/15/
Kotaro calls again, it's implied after a week. He receives one line back in a text, then calls back immediately. No answer.
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-9/16/
Kotaro says, "Since then I haven't been able to reach him... But at least I'm here." In the third panel, which implies that he's phoned more times off screen, followed by, "Ahh, the first time here after two weeks." Which gives us a timeline.
In the next page, Kotaro gets a hug, a kiss, and Ayumi leaves with no explanation, no timeline, and a promise to return that evening. However, on page 22 we see Kotaro fell asleep at 1:25 AM with no Ayumi in sight, and no message. On page 24, there is clearly daylight coming in from behind the curtain when Ayumi comes home. He ruffles Kotaro's hair and heads to bed, without even the basic Japanese greetings.
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-10/8/
Kotaro left a written note informing Ayumi of his plans. There is no response. (I'm not expecting him to send a note, but a text would do)
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-10/9/
Kotaro says, in the bottom right panel, "I couldn't reach him when I wanted to apologize." He also says, in the panel before that, that he had attempted to wake Ayumi to tell him in person, but was unable to manage it. Also, there was a montage panel again, and Kotaro is wearing different clothes. More days have passed.
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-10/15/
The friend asks Ayumi if he has more free time. More. Which means Ayumi has had it, and has just chosen not to contact Kotaro.
http://www.mangago.zone/read-manga/fushidara_na_hanatsumi_otoko/mi/099e3966120641c6472c6cb93c8b6403_chapter-11/4/
This is the first time we've seen Ayumi contact Kotaro. Our timeline tells us it's been a minimum of two weeks and four days, unless Kotaro changes his clothes halfway through the day. Likely it's been more. We have had five canon active attempts to communicate, and three passive ones, and that's assuming Kotaro has only called once any time he mentions an off-page call. There was only one response, and when Kotaro had done what Ayumi said he'd gotten two complete sentences and a hair ruffle for his trouble.
After that Aymui started calling Kotaro.
Let alone the mind-fuck that *vile* blonde dude gave him, Kotaro has plenty of reason to feel hurt. He absolutely has been ignored by his boyfriend, whom it is made clear several times has never said anything loving or possessive of Kotaro since that first, "You're mine."
Quantity is not the same as quality. Just because Ayumi started spamming Kotaro with calls three weeks in doesn't mean he's off the hook for those three weeks. Kotaro has consistently been attempting to contact Ayumi right up to the point where he's convinced he's about to get either dumped or played. Ayumi has only himself to blame.
I don't mean for that to come across confrontational. When I say, 'that's the sort of fan I am', I just mean that this is the sort of conversation I like having about the things I enjoy. I spent half of work the other day having an on and off conversation with a coworker about how not having the timeskip between Bilbo's birthday and Frodo leaving the Shire changes everything about the dynamic the hobbits have with each other and those around them. That's what I consider fun.
I agree with that. Kotaro shouldn't have ignored Ayumi either. I have to say, though, if it was me I'd have quit calling much sooner than Kotaro did, and I'd be furious and hurt when my boyfriend *did* get back to me. I really don't like feeling like an obligation, so I can be a little touchy about this. I'm more sympathetic towards Kotaro because he didn't stop contact until someone else with a poisonous agenda preyed heavily on his insecurities, while Ayumi just couldn't be bothered, but they both did wrong.
That's fair. I know not everyone enjoys analyzing things the way I do. I've had bad luck with unsupported arguments becoming mud-slinging in the comments, though, so I didn't want to leave the links out.
tl:dr would be "Kotaro has been consistently, if sparingly, attempting to reach Ayumi for almost three weeks, at minimum, before Ayumi showed any concern or reached out at all."
Thanks for hearing me out and trying to see my side, even if it was ridiculously wordy.
When you don't pick up your boyfriend's calls for three weeks, asshole! How the hell are you so busy for *three* *weeks* that Kotaro can't get a hold of you on the *cellphone*?!?
Nah, you deserved your worry, Ayumi. You brought this on entirely on your own. I'm still glad Kotaro ignored your calls, even if you've made up now. Maybe next time life gets hectic you'll have the basic courtesy to PHONE BACK!!!!
That said, there'd *better* be fluff next chapter! I don't wanna see Kotaro crying anymore!