I would agree, a date with just the two of them would be what I would work towards. Even if it's a date that starts and ends with the two f you. Sometime in between would make them have some moments together.
If this were me I wouldn't be working towards the sex thing at all. It seems far too rushed if he is not at a point where he can even hang out with her alone. It seems like it's all about the sex so far. If you want something for the long haul and something rich with connection and mutual triad love, then I think it means slowing right down and allowing the relationship to become the foundation rather than sex. Of course, its okay to just have a sexual relationship too, but it sounds like you are hoping its going to be more.
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