How's the quality (sex and the women)?
If you're banging high quality women, you're naturally going to want to spend more time with them.
There's also a case to be made for the quality of sex increasing with subsequent bangs (with high quality women), although there are exceptions to this (particular if you're a sociopath and/or have a purely pump & dump mentality, or her "quality" decreases through the deterioration of the sexual dynamics).
If you're banging high quality women, you're naturally going to want to spend more time with them.
There's also a case to be made for the quality of sex increasing with subsequent bangs (with high quality women), although there are exceptions to this (particular if you're a sociopath and/or have a purely pump & dump mentality, or her "quality" decreases through the deterioration of the sexual dynamics).