DD is the same with DF, no way would she settle for him to go to sleep even if he tried (which he usually doesn't ) and she is fine if he is with her while I'm there, but sometimes she starts crying if I go out of sight. Normally she is alright if it's just me and her and I go out of sight so it isn't separation anxiety. I think it's mostly because she spends 99% of her time with me, and because DF rarely has time with her alone, he doesn't spend all that much time with her to begin with.

Maybe have your DH play with her while you're hanging around the fringes, and just disappear for a couple of minutes at a time so she gets used to just being with daddy. Does she have regular sleep times or does she just go to bed when she is showing tired signs? I found that by about 6 months or so DD's tired signs were less noticeable so maybe he isn't able to pick up on her subtle signs? If so perhaps give him a rough time when she should be going to bed, or it may be that she'll settle for your DH one way, and settle for you a different way?