After inviting yourself into their homes and flirting into their hearts you will soon find that your relationship status can change from "friends" or "acquaintances" to "dating". (Note: Sims do not have positive results to the same interaction in a row.) To make a perfect Sims relationship and not get turned down every time you want to kiss your partner, you have to learn the balance between chatting and smooching. A very fine line of communication that is most summed up by "how come we don't talk anymore".
In a perfect game world, one could shower with their love to their hearts desire and "Woohoo" or have a "Quickie" with one's love from the beginning of their romance; but since The Sims Social is meant to mimic real life relations, your Sims won't get fulfilled just by cuddling on the couch or kissing each other all day long. Starting from the first level of dating, you kiss and compliment each other and you have to work your way up to the more intimate actions. The second level or "going steady" brings you the "Woohoo" in the shower, but don't start off with the fun stuff. Your Sims love friendly relationships and, even though you would rather be spending an hour on their couch getting a massage or playing around in the Jacuzzi, you need to make sure that they talk a little. It's infuriating to have to go back and forth from chatting to flirting, but its the only way your Sim will make it anywhere near "Soul Mates".