It looks like walking on eggsshell all the time..
You can listen from this person that you are either amazing or disaster on his/her eyes. Because value proportion for themselves changed in their mind. Ego created them new personal characthers each they or rapidly goes down to make feel them lack of self-confident.
He/she can be so sensitive, irritated and mood change with silly reasons and anxiety is appeared meanwhile. You don't predict if the next day he/she will cares/loves you or even he/she has energy and motivation to survive an ordinary day.
Because all the world (loved ones, job, things etc.) around him/her is changing according to his/her mood switch on his/her mind by overthinking and pressure of Fear. He/she impulsively and emotionally personalized it as a threat.
It is quite hard to live with him/her to wait everyday which reaction or mind respond your sentences. And how he/she values you in his/her life. When his/her self-confidence decrease significantly, he/she tries to flirt with other people to get approval of his/her attraction on his mind. However this makes him/her temporary happy and attractive because the following days he/she realizes his/her fault and feels quilty. Imagine this feeling oh gosh its really hard life.
It took long time to understand all and react calmly for the sympthoms.
We are human, have problems, worries,sometimes ups and down, stress, hopes so most of the time it is not easy to remember it and accept his/her attacks calmly.
If you really love and care this person,and sure to live forever so you should study hard to learn more and effort to support him/her. Although there is no warranty that he/she has ability to see your interest because of own priorities. Struggle a lot for achivement unless he/she rolls back you..
When he/she rolls you back that the sad part :( to loose him/her hopelessly
You must be strong enough to; first accept all negative energy with minimum damage and secondly give a support and unconditional love to him/her.
Reading all articles, studies, phycological books, and finally asking Professional support that could help you.
Ofcourse if once he/she opens his/her soul to you with love :)...
LOVE MAKES EVERYTHING POSSIBLE. BELIEVE IT
PS. Watch the great movie Silver Linings Playbook
