<human>: This may seem like a humble brag or that I'm making it up but I just want some solid  advice which reddit usually provides.  Never posted anything before.  

The first time this happened the three of us were drinking in a hot tub naked and once the jets turned on there was some heavy petting going on between them.   Next thing I know we are all making out and my dink made an appearance which led to the bedroom which led to sexual intercourse with everyone. 

Since that night we usually do it when we all come back to ours after drinking or whatever.  I'm always make sure to put more attention on my gf and to make sure that I don't make her feel jealous which sounds weird to say when I'm having sex with someone in front of her.  I kiss my gf when I'm inside our friend and I'll always have a hand or something on her.  Without getting too much into a detailed account of things, trust me when I say things get real pornoish.  They both like to watch porn and then recreate it, which sounds fun but it's actually a bit more pressure than you would think. 

Now I admit this is fun and we even talk about it when we are sober together so it's not just a drunk/high thing. We never fight about it and sometimes we even turn her friend down when we want just us two.  I won't be devastated if it ends because I feel like I've gotten enough spank bank material from it all.  

We recently got engaged and we talked about ending it.  We both think we should but we couldn't think of a good reason to other than it seems strange.  Our other friends think that it's a bit odd but they seem more curious than disgusted. 

 Has anybody had a similar relationship ?  does this inevitably end bad ?  Should I keep the party going as long as I can?  We have another friend who wants it try it with us, is that going too far?  Any advice from an outside perspective would be much appreciated.

Can you condense the text into three sentences or less?
<bot>: me and gf have 3 some friend where things are peachy.  Not sure if we should stop because we getting hitched