Hmm. As much as it could be, as per... the 3some dates... the 3some fucks....
You now have 2 women to deal with.
It could get awkward, your current GF starting shit because you "don't care about her as much as girl 2" blah blah blah. Then have to waste money on current GF to continue to show affection, loose guy time with guy friends to save relationship. Continue to prove "caring" by leading her on the marriage gripe.
Yeah. If I wasn't in a relationship I cared about, completely down.
However currently, been together for 2 years. Live together. Having a daughter soon. Not fucking this one up.
-my 2 cents.