You're probably not at much risk within a year or two of marriage if you give her orgasms immediately and start having kids after a year or two. Depending on the girl you may not be at a huge amount of risk either way. If she's high sex drive and you live in a bustling metropolis and she works somewhere with a lot of attractive men, I'd be more worried. Otherwise, so long as the relationship's good and you continue to make time for her you should be fine.
That said, you know the #1 secret to keeping a woman as loyal as she can get in any situation... keep her barefooted and pregnant!