Congratulations! As an engineering major myself, I can personally tell you that if you're dating someone who is an engineering major, you must be very lucky. Although at first we may seem quirky or nerdy, when you get to know us, and if you're lucky, are dating us, you'll realize how amazing we actually are.
We're pretty rational. And not in the pi equals 3.14159 sort of way. We try and be insightful with every situation we're put in. Analyze and analyze over again. We will give the positives and negatives of each scenario that's given or found, and base our final decision off of these factors. So if you ever get in a fight with your best friend/roommate, we'll listen and be honest when telling you that you might be wrong.
Engineers are fixers. You will never need to hire a plumber, mechanic, tech guy, or electrician ever again. We're trained in being able to absorb the situation and find the solution to every problem and possible problem that may occur. But please don't patronize us when we use the manual. Eventually (if we even need it), we'll admit to not knowing what we're doing, and actually read it. Either way, if anything ever needs fixing, your engineer can repair it in a jiffy.
We're always up for a challenge, in both the homework and relationship sense. We won't give up until we accomplish our goals. And engineers will take whatever possible route to prove it. Engineers are made for long-term. Four-plus years of college has taught us to deal with the stress and all-nighters no problem.
So if you're dating an engineer and your friends give you strange looks when you tell them this, just remember all of the positives. Your significant other adds so many positive aspects to your life/relationships.