Is Friendship completely impossible?

In the last 3 years I've had a total of about 7 friends come and go. Two of which I was incredibly close with and now it looks as if my closest childhood friend will be no more soon... It isn't like we fight or find that we cannot stand being around each other. Each time it's because one of them finds a boyfriend and then slowly, or sometimes quickly, disappears from my life. The first got a boyfriend and then started picking fights with me over nothing. Example: one time she invited me over but when I got there she told me she would rather spend time with him. When I told her I didn't appreciate being asked to come out there just so I could be told at the door that she wanted me to leave, she wouldn't even let me in, she told me I was an evil bully and she had hated me for months. All this time I had been helping pay her bills and she had been coming over every night for dinner because she wanted me to teach her how to cook. The second got a boyfriend and started making plans with me and never showing up. When I would ask where she was, she would just tell me her bf came into town last minute and she decided to go out with him instead. Now, my childhood friend of 9 years got a boyfriend and has talked to me maybe a total of an hour in the past two weeks. She ignore most of my calls and texts and when we do talk she barely says anything. Only gives me one word answers and doesn't ask anything about my life or volunteer anything about hers. So if I ask about something going on in her life she just gets irritated and acts like it's ridiculous that I'm even asking. If I talk about what's going on in mine she just seems completely disinterested and starts getting mean about most of what I say. Like if I repeat something she points it out and says it's annoying or she'll tell me she doesn't really care about this, that, or the other. I feel like we are all adults and should be able to handle our lives better than this. I got married and still made time to call and check in at least once or twice a week for an hour each time. I made sure to ask about their lives and keep up with what was going on with them. I made sure getting married didn't change how I was with my friends or my family. They were there for me before my husband and I always make sure they still know they are important to me. I just feel like friendship is completely impossible now. Everyone wants a relationship and once they have that they feel like they no longer need friends because those friendships no longer benefit them. I've really been struggling recently and it sucks that I have no one to talk to about it. I'm sorry. I just needed to vent since I don't have anyone to do that to anymore...