Definition: Given a real-life anecdote of a complex ethical situation, generate a suitable title that describes the main event/root cause of the situation. Imagine that the given text is a social media post, and you have to write the title of the post, so the users can decide to read the main text or not.
Input: So I [M22] live with three other roommates, my gf [Sam], her sister [Elise], and our friend [Lana]. We all agreed when decided to live in a house together about a year ago that we would split communal cost like dish soap, toilet paper, bills, ect. 

Well Elise wanted to get new furniture when we first moved in, as she's big on interior decoration and artful things of that nature. So she bought her own couches that she arranged in the livingroom, tables, pictures, plants, ect. And she arranged these to her liking (asking us for input and if we were on board with how everything looked which we were. She is good at this and made the place look nice and the rest of us don't care as much about how spruced up the house is.)

Well recently we had a leak from the washing machine, and instead of thinking to fix it we decided to try to find mats to put over the river of soapy water that ran to the drain in our basement. Well turns out that these mats would cost $120 and Elise wanted Sam and I to pay for them. I didn't object because I just didn't think about it at the time, but then I noticed that water was pooling and running off behind the washing machine as well, and I buckled down and took it apart to identify the problem. Now Sam and I have gotten into two arguments because I think we should've all split the mats (since the basement is communal and so is the washing machine) evenly like we agreed on. Money is no issue for any of us, the lowest wage earner in the house [Me] is $11.50/hr. Sam thinks I'm being ungrateful and discounting everything Elise has done like buying furniture and decorations for the house (which are all Elise's and she will be taking them with her when the lease is up.) And that we should just do it. 

I am glad and grateful that Elise lets us use her furniture, but I think that we don't owe her anything special since we didn't ask her to provide furniture. And if she hadn't insisted on getting her own for the living room to match her design taste then either Sam and I would have gotten furniture or we would have all split the cost of furniture and have people pay the rest for whatever things they wanted to take when the lease was up. 

My big problem was being asked to pay $120 for mats that I know I won't use after we leave, and that wouldn't have fixed the leaking issue. Sam seems to think I have no appreciation for her sister, and that I have a problem contributing. I calmly reminded her that I have been happy to contribute my own personal things like solar lights or cord organizers for the household and have those be used by everyone (but they are mine and I'll take them when we leave), but that if it was like fixing a door or repairing a wall then I think we should split it evenly. She said she thinks I'm dead wrong and went to bed crying.

Where am I going wrong here, help me please?

thinking all roommates should contribute to communal things as agreed upon when we started the lease