It means that the person who sent it thinks that you are notnecessarily a loser, but are not as cool as the 2 other people they're currently having sex with.. You just aren't as good as 3 people are, and you can't do what 2 additional people can do for them
Emo: hey can we smash?
Person you want to smash with: <3 (sorry you're just not as good as the menage et trois I'm having, loser)