Sure (and who wouldn't find Ellie attractive), but this doesn't contribute in any way to Sam thinking he could make Sophia jealous by flirting with Ellie. In fact, it would have just the opposite effect.
If you go on Aiden's third task then the invite to Cathy's happens after Sophia leaves, so there absolutely are ways that Sophia doesn't know about it. To my memory Sophia hasn't had any contact with Liam after the bridal shop and I don't recall her ever communicating the concert to Liam. That Sophia is on board with the evening Cathy/Andy visit if she doesn't go on Aiden's 3rd task (and stays at the bridal shop) is immaterial, or should be if the paths are to be truly divergent.
I envision, most probably, Liam will simply assume she is readily available for him at a moment's notice, especially on a weekday evening, and that she would have no objections. IMHO that's a totally Liam move - completely oblivious to how that type of assumption would be interpreted by his wife and totally incapable of respecting her independence and autonomy. Similar to what
hzjujk proposed, I could totally see Liam calling Sophia and telling her it's time to go to Cathy/Andy's place and she's completely unaware, gets into a bit of a "WTF Liam!" mood, which could nudge her even more towards giving into temptation as a way of getting back at Liam. This could be especially true if FW is really high and GW is really low, and would be a reward to players who have intentionally pursued such an unbalanced scorecard.
Not making a prediction here, just laying out a plausible scenario.
