Yea, I'm at the point where if Gale or Wyll want to 'talk' to me, I just immediately say "not interested, bye".
As I said in the OP, it just gets worse the longer you go.
I had Halsin suggest a threesome with the character my character is romancing(yes, all these advances towards my character are while he is romancing a separate person!) after I've rebuffed Halsin two or three times now. I benched Halsin because he's so damn horny.
For anyone looking for advice for what companions to use for minimum horniness:
Shadowheart, she's not very forward at all. I think she's the best written companion overall too, so that's a bonus. Without spoiling anything, the female druid. You'll know it when you see it. As for a third, I don't have a good suggestion here yet, but I have a feeling a companion you get in the city is going to fit well here. Too bad it takes so long to get that person.