There is not such a thing as a person who worships you day and night, forever and ever, no matter how you treat him. Well, maybe there is, but unless it is reciprical, I wouldn’t wish that on any guy I know!
Marriages have ups and downs. But is there such a thing as a man who will treat you as well after marriage as when you were courting? No guarantees, but sure there is.
Will your choice be one of those guys? The best way I know to find one is the following: look at how he treats those he already has “in pocket”, especially his mother, and look at how his dad treats his mom. Those are your best indicators. Also, look for someone whose friends and family are people that you like, too, someone that gets on well with your friends and family, too. If you don’t, you’ll both have a tough row to hoe. Once he’s over the initial infatuation, he’s likely take your low opinion of his hand-picked friends very personally, and vice versa.
If your parents had a bad marriage, if you’ve never had the chance to see a great marriage up-close, then you need to make an extra effort to get yourself into a mature and giving frame of mind. If they had a good one, though, and if you marry someone whose parents had a good marriage, you are off to a good start.
Also, remember that you never know the whole story about what is going on between married couples. Don’t let that scare you. Give your sister another person to lean on, hear her feelings and let her vent without taking sides, and chances are that her marriage will right itself down the road. (That’s when you’ll be glad you didn’t pile on your BIL when she was grousing about what a louse she married!)