Complex sentence: For most of the series' run, Raj had not been involved in any lasting romantic relationship, mostly due to his inability to speak to women: however, he was much more successful in casual sex than the more sexually aggressive Howard.
Split into simpler sentences: For most of the series' run, Raj had not been involved in any lasting romantic relationship, mostly due to his inability to speak to women. However, he was much more successful in casual sex than the more sexually aggressive Howard.