1. If she suddenly becomes to busy for you.
A healthy relationship requires time to bond. If she suddenly start giving you excuses of being too busy and and cant make out time to see you, this is a very good sign, somebody else is taking her time. If she is too busy for you, she is certainly not busy for Somebody else.
2. If she stays distracted when around you.
If she doesnt pay attention when around you anymore and doesnt want to have a good conversation with you, she is definitely not into you anymore. Her mind is probably thinking of somebody else.
3. If she doesnt comfortably answer her calls in your presence.
A healthy relationship requires partners to be free and open to each other. If there is a sudden situation where she doesnt answer her calls comfortably in your presence, most especially when its another guy calling, then she might be seeing that guy.
4. If she switches off her phone or put it in silent mode
There must be something going on that she wouldnt want you to suspect. So the best way not to answer calls that will rise your suspicion is to switch off the phone. If you find her phone off or on silent mode whenever she is around you, then she is cheating on you.
5. If she seems not interested in your plans or future
If she starts giving you the attitude that shows that she is not interested in your plans. If she doesnt seem to have anything to say about the future anymore, if she doesnt urge you to get better or look good as she used to, then she might be into somebody else.
6. If she doesnt want anything intimate with you anymore
If she doesnt want to get intimate with you anymore or you find yourself trying to convince her to get really close to you, then she might be seeing someone else.