engaged but free

so i met my current fiance like 6 months ago and we been going strong since. shes in her late 30s too so not a huge gap. anyway, long story short, wenever spend the night apart now or anything. but lately ive been dreaming about this other chick from back in the day, before i even knew my fiancé existed. like fully explicit dreams where im banging this girl all over the place. one time she actually came over to visit last weekend and we just ended up having sex on the couch for a couple hours, clothes off, everything going wild, nothing held back. afterwards we both were kinda freaked out but still into it, so now i dont know how often im supposed to let this happen or if its weird that i actually enjoyed it more than normal married missionary style stuff? any thoughts?