Crashes occur randomly

I have been playing Minecraft for what feels like my whole life. I have never had problem with it and love the game. I think it is my favorite game and I’m am very satisfied.  But, just recently I was playing with my friend on a survival world and we built a nether portal and lit it and my game froze. I didn’t think much of it thinking it was just generating the nether so I reloaded the game and it was normal until my friend joined and it froze again was now a little confused. I thought it was the portal so I broke the portal and it was normal. Or so I thought.  Again my friend try’s again still crashes. I wondered if it was the world so I went on a different world. Then it crashed but no one was joining. Now the game randomly freezes at different points and unable to play the game. I love this game and hope it will be fixed. I hope I can play this great game again.