lol, I have no clue despite 9 years in, with 7 being regular force, here in the CDN Forces. So, the times I was deployed, I had open relationships anyways [I don't do exclusive to begin with] and thus it really made no difference in the "cheating" dept. Emotionally, I really missed my GF when I was gone. But alas, I just fucking dealt with it. When inside the wire at K.A.F., phone and IM/internet was readily available and I talked and chatted and sent photos back and forth a lot. The risk never really bothered me as such. Yeah, I was scared in the moment when it becomes a two way firing range. But in general I don't really give a fuck and the risk is very slim.
Again, I don't know about the U.S. benefits and pay, but here it is quite good really, and generally any given MOSID is on par with a civilian of an equivalent type of occupation, with many adjustments for anything remotely specialized. I am commissioned and actually make quite a good amount of $$ and my job is quite enjoyable TBH and I am located in my dream location and there is no foreseen reason why I would be sent anywhere else except for an overseas deployment. [keep in mind we don't have generic non-mission oriented bases like the US does in Japan and Germany etc everything is for some sort of undertaking with most being tiny U.N. observer related deployments]
My current G.F. is also in the service, granted in the Reserves [Which in Canada are very different and essentially you can fill out a form, turn your kit in and leave, no questions asked, and the Reserves have not been forced into deployments since I think Korean war] and in such an unrelated command and holds the same rank and thus is not frat.
Over all, in my personal experiences, being in the service has had little to no impact on my relationships and has otherwise been a fucking awesome occupation and I am not leaving anytime soon.