" she knows I love her", " c'mon I must not tell him that, because he knows I love him". When you are used to that, gradually you are destroying your relationship unless you are done with it. Then that can be your break up strategy.
Rejecting your partner's calls without explanations just because you are busy might start building up the wrong thoughts in the person's mind. Instead of rejecting the call, allow it to ring. Afterwards, send a message but if you are not opportuned to type, maybe you are in a meeting after that please call immediately. That's the more reason why you should always carry your partner along it will help them know how important they are to you.
Please value your relationship. Remember how you started with the person instead of allowing that to die rather, strive to do better.
Actually, it hurts when someone loves and is faithful yet they are not reciprocated for their affection.
ADVICE
You just read this or maybe you had to scan because of time constraint or whatever the reason may be. Please call that person you love now if he or she is far from you, if the person is close please tell him/her how much you love them and how meaningful they are to your existence. Please do it now!!
OK. That's good advice but sometimes it is not easy to tell.