Relationship/ friends

Honestly idek if it's just me but I don't understand relationships. Like it scares me to think of devoting myself to someone forever, and my friends in relationships are constantly fighting with them, and it's gotten to the point where I don't want to hang with them or listen to them because all they do is talk about how their boyfriend sucks and all this other shit. Like my one friend has cheated on her boyfriend several times yet cries everytime he thinks about leaving her. Another one , her boyfriend had cheated several times and constantly does shitty stuff and all she does is complain about it when she's with me, then like five minutes later will ask me if it's okay she ditches me to go and hang out with him. I need a place to vent right now bc they are my only friends, and I'm honestly thinking about cutting them off. Please give me advice and I know that I sound prissy and stupid and this turned into a rant but I literally have no one else to turn to about this. 
Also idk if this was the right place to put it under I'm sorry if it isn't