I think Sallos would do just fine. Look through as much information as you can on Sallos. You can put Sallos’ name in the search bar on this forum and get some hits…you can check the BALG Repository under the Love Magick heading to see if I’ve got any success stories involving Sallos there, and you can do a google search to find any extra info you can in terms of what kinds of offerings Sallos likes and such. If you do this, you’ll build a relationship with this spirit in your mind before you even do a single ritual…and you will feel much more sure about your choice. And if what you read up on Sallos doesn’t resonate with you, you are always free to go with someone different.
As for them doing “the nasty” lol…Well, if they’ve been together for a while as you say, there’s a good chance that they’ve already done it tbh. I wouldn’t linger on that thought too long. It is what it is. Your focus has to stay on breaking them up and bringing her back to you.