There is a smut manga that I have been looking for...it is a one shot and it start out with the girl saying that the first time her and her husband had sex, she was crying and how after that, they never had sex again.

Basicallyyyyy,
★ The girl wants to be closer to her husband...but he distances himself from her.
★ Her childhood friend has a crush on her and hates that she had been forced to marry some older guy.
★ The girl chooses her husband over her childhood friend at the end...t'was a nice happy ending...well...except for the childhood friend ^^;;

Anyone know what manga this is?

Also...

Any good steamy smut suggestions?? (　★3★)/　

I can only answer the second query, not the first though, although there is a manga about married couples called Futari Ecchi (haven't had the chance to read it) but it could be what you are looking for. Warning: Ecchi and Borderline H, just in case these are not what you are searching for.

Well you did mention steamy smut, there is Hapi Mari so anything by Yoshihara Yuki plus her theme has married couples or going to be married at the end of the storyline, so I hope this would fit your criteria. 😀