I understand. And who is to say she won't interpret it like that? At the same time, your own needs of the frequency and duration you guys spend together has changed, which is okay, and normal. I like some of the other posters' responses too...you don't have to pick up the phone when she calls. You can text her and say "I will call you tmrw" or some variation. If you are direct, or somewhat direct, you don't have to give the real reason for wanting to lessen your guys time together. Though I say...keep it kind and gentle, if you are wanting to keep the friendship. I also think its not your responsibility how she interprets it. But I understand fearing losing her. If you choose the direct route, you can tell her you value her friendship - But that things have shifted for you a bit and you are spending more time doing x instead. Not sure how that lands for you? You can also just not pick up the phone, like another person suggested.