Do relationships work out when girls say they dont want sex until marriage?

Now im young 18, and i know in a lot of other guys minds when we get into a relationship we are looking to get it in, just being straight up if a guy sais he's fine with waiting until marriage he is either 1. low key gay, 2. an liar, or 3. going to be in a relationship with you but be sleeping around on you. I have friends who have said they tried it but within a month and a half or two months they dropped the relationship. I just want to know from peoples experience with this if they actually put up with it. to me its like impossible to be in a relationship and not get physical, its not going to last long, im not saying get it in on the first date, but if you got to wait 6 years before you let your man in, he gonna be gone in a few months.