Has she ever given you a hairjob before? Just curious.
Here are some links that may help you solve your problem:
menshealth.com/sex-women/a25935997/how-to-stop-an-orgasm/
selfgrowth.com/articles/i-climax-too-soon-during-sex
theguardian.com/lifeandstyle/2009/jun/25/sexual-healing-climaxing-too-soon
mensexualclinic.com/stop-yourself-from-coming-quickly