Complex sentence: Erection, orgasm, and ejaculation can each occur independently; however the chance of ejaculation seems linked to the quality of the erection, and the likelihood of orgasm is linked to the ability to ejaculate.
Split into simpler sentences: Erection, orgasm, and ejaculation can each occur independently. However the chance of ejaculation seems linked to the quality of the erection, and the likelihood of orgasm is linked to the ability to ejaculate.