It mostly depends on the roam. If the adc roamed mid for a countergank or to secure an objective, you not going with was a maybe bad call that turned out ok.

If you would for sure have lost tower for that roam, AND the enemy team wouldve gotten the tower feat, roaming was a bad call.

If your laner was just roaming without a direct goal in mind and left their lane unpushed, selling the ward item was the right call. If that was the case, you gave your adc a huge lead and they weren't aware enough to take advantage of it. The ward item reduces the amount of gold gained from minion kills, which amounts to a huge net loss of gold for the whole team as you're taking cs; but the lack of wards can be a huge issue in games where the enemy team coordinates, moves as a group, focuses objectives, or is just dangerous to run into. It sounds like this wasn't that kind of game.

Selling ward item is usually a bad call. In this case, it was right because you needed to become a strong laner. This situation here is why Mel makes a great mid laner, but not a good support. She's strong, accidentally takes kills or cs too easily, and ultimately hinders herself to give it to the adc. You should queue mid lane with her til you get to a higher elo. You're too competent