I find it funny that this is only place that people are moaning about Raph and Mona Lisa. I haven't seen any one moaning about it on Tumblr.
Anyway they weren't even kissing, they were bumping noses.
Don't worry guys, we got 5 episodes left of the space arc and then we probably won't even see Mona Lisa agian, so poor Raph won't have a girlfriend no more.