My partner is a groomsman, i don't know if I'm invited

That's terrible etiquette, but not on your part. You need to be invited to the wedding as his SO and also to the rehearsal dinner. Since the couple didn't make it clear, your partner is well within his rights to contact them and ask. If you aren't on that guest list, I would think he'll need to reconsider that friendship.

How far out is the wedding? The general wisdom is to ask people to be in the bridal party about 6 months out (and plenty of people ask way further out than that), whereas invites go out about 6-8 week from the wedding. He may not have been given an "official" invitation because they aren't there yet. If the invites haven't gone out yet, I'd say just be patient. It's proper (not always done, but proper) to invite significant others of bridal party members, and that includes to the rehearsal dinner.

If the invites have gone out and they just figured they'd save a few bucks by not sending one to your significant other, then he definitely needs to ask if you're invited. It's way worse to just show up to a wedding than to ask ahead of time. The invite would have been the indicator, and if that's not there, then there's really no way to be certain.

I'm pretty sure you're invited. . As others have noted, it would be a huge breach of etiquette if you weren't-- a regular breach as you're his partner, but now enormous since so many details have been casually discussed around you. That's what makes me 98% sure you're on the list. I could earnestly see so taking for granted that any one of our wedding party members' S/Os were obviously invited that I wouldn't have made it expressly clear. However, gently asking your partner to confirm w/the couple is absolutely ok to ease your mind. It's also fine the next time you're with the bride to pull her aside and sweetly make sure you're actually invited-- there's a way to say this bashfully and earnestly without at all being "rude." I think any bride but a complete a**hat would be horrified to know you'd been feeling so uncomfortable. I'm just a couple weeks out from my own wedding, and can say that many folks (well outside the realm of ANY relationship status, let alone long term) have asked us about plus-one status, and we're completely ok being up front about it. We were also thinking about seating plans long before rsvps came in-- we had a good idea of who was very likely to come, and couldn't help anticipating it. If you aren't at the head table, as others have noted, dinner will just be for a short period of time-- and you'll likely meet someone new, enjoy the opportunity to connect! That said, as others have also noted-- sweetheart tables are pretty common these days; you may not even have the issue. Combo advice: relax, but also: take initiative to be direct-- with both your partner and the couple-- you can put a stop to feeling icky and start (most likely) getting into the celebratory spirit, or (very unlikely), begin coming to terms with a bad situation you don't deserve to be in. Either way, limbo is the worst option, so you should make a move now. Best of luck!