I live my life in a Poly type Relationship.. I will admit it takes a lot of work especially when  the second partner lives out of State.. From my own experience , a Poly relationship can work. The only thing I would seriously suggest is that you choose a second partner that is local, that way you can actually see each other, and not just facetime it everyday. I was able to visit my second partner one time, because they are 12 hours away.  Also, my relationships are not considered one relationship, but two separate relationships. The best way that you can keep the other person happy , is by trying to include them in everyday life, text often, send naughty photos. Open communication is key, always be transparent in all that you do, and above all you have to be able to trust each other. If you don't have the communication and trust, it is not going to work. Their may also be times where you can sense a bit of jealousy between partners. You need to make sure that you reassure your partners that you love them both , and that they can openly express their concerns at any time. Where their are children involved and you know that both relationships are serious, you can reassure your children that they have an additional person in their life that cares about them,and will always be there for you .My children are 18+ so they were able to give their input, and voice their thoughts freely.They also understand, that that type of relationship dynamic is not for everyone.