When my wife and I tried poly briefly, it did, for the most part, bring us a lot closer to each other. We communicated more, we were even more intimate, and our sex life was enhanced.
Some of this was shared excitement, some NRE. In the end, our poly "experiement" ended with the negatives outweighing the positives.
We'd never gotten so far as me introducing my wife to one of the women I had gone on a date or 2 with.
Since then there's been a lot of healing, and a lot of soul searching. I do not know if there's any poly future for us, but we've gotten back to a stable place.
But to your original question, yes. It brought us much closer to each other in the beginning.