I am the same way. When I used to get high with my girlfriend, I would suddenly see our interaction in a completely different and not very positive light. For instance, it would seem like we were just using each other to relieve our feelings of existential loneliness and insecurity. But its true I had very shallow relationship with that girl. I dont know if I'd have felt the same way with a girl I truly loved.
Let me say a few things though. First of all, you need to understand that love isn't a feeling.
http://aldersgate.net/love-isnt-feeling/
http://theupsidedownworld.com/2013/02/28/love-isnt-a-feeling-its-an-ability/
read those links. If you want to really love someone, it has to be from a deeper part of you than just your feelings because feelings always change. It sounds like you were just getting high on emotional feelings of love (which is very common in our society) and then when weed killed your love buzz, you didn't know what hit you.
Another thing I should mention is that you have to understand the way in which drugs provide information. Weed gives you a different perspective on everything. By seeing everything in a different light and then comparing it to your former light, you can realize some truth. But you shouldn't assume that what weed shows you, is the final truth. Its just one possible perspective on things, which fits into a whole of virtually unlimited potential perspectives. In my experience, weed is very much a mind drug which will make you see through how your mind is working to create your emotions. THat can be unsettling because you see there is no love/emotion in objects, its something you add.
But you have to consider other perspectives also. FOr example, if you had taken mescaline or MDMA with your boyfriends, you might have experienced tremendously increased love for them and more bonding. This is because those drugs activate the heart. The heart is where your love comes from, not the mind. If you learn to live your life more open hearted, you will experience increased ability to love. You will see that to love is actually a God given ability and it is not dependent on the whims of the mind. So marijuana shows you the silliness of the mind, whereas mescaline shows you the stability of the heart.