Ever since I developed my first serious crush on someone, I have been struggling with obsessive thoughts about current crushes ending. Basically, as soon as I fall in love, I automatically start worrying about falling out of love with that person. These obsessive thoughts make it impossible for me to enjoy the actual 'crush' period of any relationship. Whenever I look at the person I am in love with at the moment, I am automatically filled with dread when I realize they will not continue to give me 'butterflies' forever. Weirdly enough, I also get these thoughts before I even enter into a relationship. 

I know that a more companionate type of long-term love can also be fulfilling in its own way, but the very thought of entering into a phase like that with someone I am currently in love with is unbearable to me. I have not been able to simply accept the fleetingness of crushes/the 'honeymoon phase' despite having really tried for years and also bringing it up with my psychiatrist. I spend a lot of time reading about buddhism, and thinking about the transitory nature of almost everything, but I just keep getting upset when it comes to the demise of 'new relationship energy'. I have several close friends and dear family members that I love, but romantic love without the limerence seems to me to be completely 'empty'.
Do you experience anything similar to this? Does anyone have any suggestions? These thoughts are seriously ruining my social life and are making me want to never enter into a relationship at all.