Welcome. You didn't give genders of the people involved (if you meant to conceal gender, you slipped up a bit in the second paragraph with your first pronoun....for the rest you use 'they/them').
So, if you present as female and your partner presents as male, you will almost always get more attention than your partner. Yes, social skills will contribute to this, but they don't apply that much to dating apps (a little, AFTER the match, but not before). This is a very common problem in poly. Women can easily find partners (though finding GOOD partners is a challenge regardless of gender). Men have difficulty for reasons you can find with a bit of research (and probably just think about a bit and realize, to be honest).
I am going to give you two anecdotes of similar situations. Whether they help or not is up to you. The first is my own. My wife (cis-woman) and I (cis-man) opened our relationship about 5 years ago, at her request. Well, I was open to the idea the whole time, but I didn't push it on her. I waited until she asked. Anyway, we were both pretty busy at the time, but she actually had someone in mind. After that initial encounter, more opportunities arose simple 'in the wild' (meaning without dating apps). These were ultimately problematic and led her to use apps to find partners. Long story short, over that five year period, she's probably been with 6-8 people, sexually, and fell in love with at least one of them. That one didn't work out for reasons that are private (to her, not me). I vaguely tried to match on some dating sites, but not very hard. I got a few matches, but they went nowhere, and covid happened, and long story short, I went through all the feelings of 'she has lots of options, I have none!'.
This year, I decided to try for a change. I downloaded feeld and OKC and actually put what I wanted and made some efforts to match/talk to people. I had three dates within a month (ie. by the start of February). The first two went fine, but nothing major. The third was a love connection. Her story is next. But my point here is that my wife has 'gotten more' out of poly, if the goal is lots of partners. However, I'm the one with a second partner whom I love and is a healthier relationship than she has yet have (that's a bit unfair; some were healthy, but temporary. This one seems more likely to last the long term). I don't think these comparisons are very helpful. She's had more partners. I've had what I want. We are both good.
Flipside. My new partner has another partner. He's having a hard time with our relationship. Why? Well, from his perspective, they opened up the relationship so that they could both enjoy new sexual experiences, mostly with each other (same room, maybe some swap). My new partner didn't have a ton of experience, sexually, because she married young and then divorced. So, he saw this as a way to provide that for her while also exploring ENM himself. What he did not expect (nor did she) was for her to fall in love with someone. She's thrilled about it ("I didn't know this was even an option!"). He's less so. Again, not totally fair. He's happy for her but envious. He's probably also a bit scared that she might leave him for me (I don't want that; she doesn't want that either).
Here's the thing. When my spouse or my girlfriend (for lack of better word) open up an app like Feeld, they have 300 likes to choose from. As a man, I don't, and I'm reasonably attractive for my age (with steady finances, etc.). It's the nature of society. This gives them more options, but it also means they can be very selective. When your partner DOES find someone, they can be pretty sure that the person is into them (if they stick around, of course), because they definitely have other options.
All that said, I'm sorry this is hard for both of you in this way. Have you considered being a wing person, so to speak? My wife is happy to give me advice on dating (and my gf would be too, if I wanted to find another partner as well, but right now I'm pretty focused on my current relationships). Some people meet others as couples, and if people hit it off as pairs, that's great too! There are MANY ways to be poly.
