Complex sentence: Jeff and Steve have been friends at least since high school, he met Susan at work and they attempted to hook up yet it abruptly ended when Jeff suffered a panic attack due to being so nervous about having sex with her.
Split into simpler sentences: Jeff and Steve have been friends at least since high school. Jeff met Susan at work, when they attempted to hook up but failed when Jeff suffered a panic attack due to being so nervous about having sex with her.