To the OP
I live with my iphone. It is attached to my inside left hand and only leaves it to get charged. When I get a text I jump on that so fast they didn't get a chance to close their own phone lol So yes anyone who texts me and doesn't get an answer back very fast knows its because I can't.
Regarding your situation. I am with you on the frustration and yes it feels bad. But most women help books tell us not to answer back quickly. To wait hours and sometimes two days in a new relationship. I say eff that I will do it my way cuz I will never bait and switch anyone lol But just keep that in mind, its in the training manual lol
Also if your text did not require a reply then she will/may not reply. I do not reply to texts that do not require a reply. Same with email. And if I send a text that is closed "you have a great day" " Ty for the info ttyl" and they still text me I will not reply. Text sucks for new relationships I am firmly against it.
Pick up the phone and call her and leave a voice mail. Plus because we all use speed dial maybe she lost her phone? Maybe your text never went through? Just like a fax, just because it went out of your machine and said SENT doesn't mean the other party got it
Just try to relax and dont get up all in her sh*t just yet. Maybe its on purpose. Maybe its not.
Just because someone asks you a question doesn't mean you have to answer it. Just because you receive a text, message, letter or email doesn't require the receiver to respond. People respond because they want to. Dont get all bent out of shape because their time line doesn't work with yours. If you cant handle that then you cant handle the girl/guy. If its on purpose then you dont want that person lol
Add: I realize I am a little jealous and do require attention when I ask for it so for me I may be a little more strict on this stuff. That is why I understand you.
Lettuce know what happens please

Hope it works out the way you hope
