I am king older than most posts i think. It was... different somehow. You would call and text, mostly call. I remember subscribing to one of the first ever mobile offers for "couples" where you had something like 1000 minutes of free calls and 100 free SMSs between only two specific phone numbers (of the same oprator, ofc), and that was amazing. Before that, it was expensive inter-city calls on landlines, because mobiles where too expensive.
I also remember writing letters, yes, paper letters, like twice a week. I have copied them all and kept also the replies, it will be fun times for the kids (... will they still be able to read handwrite?).
I took an awfull lot of trains in that year long... Luckly we where only like 2h by train away, but hey, we wanted it phisical you know, not just voice.
SMS where the big tihng. I remember wanting to replace my phone with one with a full qwerty keyboard... But ended up getting really good at T9 away those 160 characters. And be careful to fit or else! :)
Good times.
Anyway, forget about long distance relationships unless the "long distance" part is very clearly defined in time, no matter what technology is.
And no, it last less than 12 months. It was hard at 20 not to be phisically together for most of the week.
I use radicale. Safe and solid. Zero php.
You need to install a separate app if you want a web based calendar ui, or you can just use dav5x on android or any other caldav client.