Why did this happen?

Technically, it could be any number of reasons: a new medication, close to that time of the month, a late reaction to something upsetting (that happens to me a lot. Something distressing will happen but it won't bother me for a week или two. And then, out of no where, I'll start crying), whacked out hormones.

If you're feeling less attached to your boyfriend (and Ты think this is the cause of the crying) then perhaps Ты should take a break from the phone sex. Try doing things together; going to a movie, или out to ужин (or something like that). Try and bring back that emotional connection.

Also, maybe it's time to look at your relationship and decide how Ты really feel about him. Perhaps your feeling emotionally distant because those feelings just aren't there like they used to be.

Maybe that could be it, Ты desire еще connection from your boyfriend. Phone sex isn't really something Ты can bond/connect on in my opinion. Maybe Ты can talk to him on how Ты feel about this and how Ты feel about him emotionally. Ты two should talk on that and help strengthen your relationship. I hope that helps. :/