Not really. :/ The best thing you can do is ignore a phone fling. You don't have to do it if you don't want to. Did you finish it already?

If you want to be free of the 'new text' alert, just let that fling autoplay for a bit while you do something else, & just check back in to see if you have to give a response. Don't even have to read it, really.
But yeah, it'd be nice if you could just. Block their 'number'.

引用自 rosesnowflakes：

If you want to be free of the 'new text' alert, just let that fling autoplay for a bit while you do something else, & just check back in to see if you have to give a response. Don't even have to read it, really.
But yeah, it'd be nice if you could just. Block their 'number'.

There's a reason behind why you can't block: because every fling character can become a datable character in the future and you need to finish their flings to get them once they're unlocked. It was the case with Ace, and the studio made a poll between if I remember right... 3 or 4 characters to vote for and make them the next one availiable (and unlockable) ^^