One of the many things I've learned about women in my short existence is that they usually keep a "guy on deck." Meaning, if things go awry with their main boyfriend, they have a few guys who they feel are available to take his place.
Your relationship with "Carmen" was one of that nature, you were the "break glass in case of emergency" man. So when Andrew, her part-time boyfriend when he wasn't Marcia full time husband and father of their 2 kids, decided that he needed to spend more time with the wife and kids.
Carmen began to see the "writing on the wall" and that there was more to the "I'm just with her because of the children" was nothing more than a line.
Therefore, when she invited you over to look at a lamp that was malfunctioning, you figured it was nothing more than you playing the role of the handyman. After arriving you take a quick assessment of the lamp's condition and realize that the socket needs to be replaced (fortunately, you brought over a new one).
You tell Carmen that you should be able to fix it and she sounds relieved, and offers you something to drink. You're not sure what she has so you ask her what does she have to offer? She tells you to come over to the refrigerator and come look, and you do while Carmen is standing in front of the fridge.
You're not really sure what prompted her next move, maybe she was missing Andrew? Maybe she was just horny?