To create a sectional sofa look, you must minimize the arms.
The ideal situation is a one-armed or armless sofa and love seat, which allow you to create a matching sectional grouping, with an ottoman at one end of the sofa that elongates one side. The opposing love seat forms a U-shaped seating cluster. But even with one-armed sofas and love seats that are designed to serve as sectional furniture, an ottoman at the same height and with similar style characteristics fills the space between the sofa and love seat, linking the pieces to create a unified space.
When a sofa and love seat are not designed to serve as sectional furniture, ottomans help to establish a sectional look. An oversized sofa with arms pairs with an ottoman to provide a sectional look, particularly if the ottoman is the same height as the sofa and has a similar composition, including matching fabric, such as an umber sofa and love seat with an umber ottoman. Matching upholstery unifies the elements of a faux sectional grouping via color, and large, strategically placed pillows help disguise the arms.
If your sofa and love seat are smaller and more tailored, the ottoman solution still applies, including for sofas with exposed legs and narrow arms. Two small ottomans create a U-shaped space, especially when the sofa and love seat arms touch at one side, providing room to insert a third, matching, exposed-leg ottoman at the same height in the groove between the sofa and love seat to close the space from behind. From the front, on opposing sides, two more matching ottomans form an intimate cluster.
Create a causal, multicolor, sectional-style grouping by pairing a matching sofa and love seat with contrasting ottomans in a complementary hue, such as a plum-gray sofa and love seat with mustard ottoman. Place a mustard ottoman of the same height in the space in between the love seat and sofa, making sure the ottoman's leg style echoes the legs of the sofa and love seat; then add a matching ottoman at the end of the sofa's front cushion, peppering the faux sectional grouping with mustard pillows and accents in grape and lemon yellow.
, Anya. "How to Arrange a Sofa and Love Seat Into Sectional Furniture." Home Guides | SF Gate, http://homeguides.sfgate.com/arrange-sofa-love-seat-sectional-furniture-105995.html. 18 September 2015.