Just keep rationalizing it any way you can.
If you were "happy" being "single" you'd be driving a Civic and not that pussy magnet vette of yours. There are many levels of a "relationship" and all those levels satiate certain needs we all have. If you have a one night stand with someone you are still trying to satisfy an emotional need for attention, affection, and "love" from a companion. Even flirting is a form of a relationship. You feel good while flirting because you're interacting with someone on personal/intimate level, and it makes you feel good about yourself because you have someone around you, even it's only for a few minutes.