your partners in poly relationships are among your best sources of support and advice. they know you, and they likely know your other partners pretty well too. your metamores (partners partners) can also help, as everyone in all parts of poly relationships should want everyone else to be happy (clearly they don’t want someone their partner cares about to be unhappy)

(that said, since yall are relatively young with poly things, they may not have your best interests at heart i guess… they might see your communication as a way to drive a wedge between your partner and you so they can have him all to themselves… that is incredibly unhealthy, and if they do think in any way like this the poly relationship won’t last in the long term: metamores all have to share)

communication is always the biggest thing. speak your needs, and don’t assume that they know how you’re feeling

it’s also more than possible that they just express their relationship differently. perhaps there’s things that you and he do that his boyfriend is envious of too

try and figure out if behaviours are actually things that you want or if it’s just jealousy… jealousy is something you absolutely need to get over for poly to work: try to develop that into compersion: be happy that your partners are happy. if you can’t, that’s fine too! but don’t let it consume you. in that case, the relationship (or poly in general… poly sounds great in theory, but takes a lot of emotional maturity, knowledge of yourself, and just plain work) might just not be for you - yet.

again, you have another partner: use them for support, either to work out your needs and then how to communicate them, or to deal with the emotional fallout if things don’t work out