Interesting. Because of her position, Picard has a more personal working relationship with Troi than with anyone else, but I think that would cause him to actively avoid considering her as a romantic partner. For one because he can’t afford to lose her counsel. But also because he needs to be able to talk to her about anything and everything, and that level of trust is difficult to maintain in a new relationship, or one that is going through growing pains, and certainly after it has ended. And while I think Deanna’s boundaries are more fluid, she would sense and respect this.
So at least while she was assigned as the counselor on his ship, the only kind of sexual relationship they would engage (heh) in would be of the purely physical and consciously separated from both their work and their friendship kind. Basically avoid all feelings. And I think that both would be more likely to choose someone else for that. I’ve said before, I think Will and Deanna absolutely had sex whenever they wanted to and weren’t otherwise attached – they aren’t precisely avoiding feelings, but they don’t let feelings get in the way because their relationship, whatever it is at any given point, is already established. Deanna is also close to Tasha, Beverly, and probably at least 200 people we never see. Also, I would really love to see Deanna and Data in this kind of relationship. Like, she’s teaching him to connect the physical to the emotional but they keep things physical and not emotional – that paradox, involving the man who “can’t” feel and the woman who “can’t stop” feeling, would make an amazing story.
Jean-Luc is in a tougher spot as Captain, but he has various casual relationships off ship and if he ever really needed someone Q would be there in the flash of an eye.
And she only leaves that assignment when she gets married, and Picard canonically respects the institution of marriage regardless of his own feelings. That said, and I’ve also mentioned this before, I am 100% on board with a Will and Deanna and Jean-Luc and Beverly scenario. They meet up for vacations, spend holidays together, are always the first in line to rescue whichever ship is in danger, and eventually, in retirement, live all together at the Picard estate in France. All is right in the world.