She's a cracker alright and it wouldn't be unusual to think that a smokin' girl like that would be likely to cheat.
However looks can be deceiving, you know her better than anyone on here so if you think she is a keeper and you're into her 100%, then go for it.
On the other hand, you get the slightest incline that she messing around, ride her into the ground and then give her the boot.