I've come across a few, promoting both couples but are sharing the links of the two best sites, IMO.
If you wish to search on your own further, then they can via the several links posted onto each website, though, I'm sure most of you guys know that to begin with.
This site is mostly Ed/Winry art along with general FMA art.
This is mostly Roy/Hawkeye art.
I'd like to thank yankeerose69 for being so kind as to sending me the initial links that enabled me to find the two good sites I did.