If you were to take the deal, it would cause some serious grief in your life overall. A lot of people are posting that they'd hate to see all their loved ones die, but it would be highly illogical for you to stay with anyone for much longer than 6-8 years because they'd become aware you're not normal. At a certain point you'd have to cut ties with your family or they'd realize you're not aging. I mean if they really love you, I guess they'd accept you, but you can't be a normal husband or wife, father or mother, or son or daughter because of what you've become.
Most likely you'd live out your family and after that point work your way from place to place, lover to lover, without letting anyone see who you are or get to know you for too long. Now if you're prone to falling in love, it would become a continuing problem because, as I said, you'd eventually seem inhuman to your spouse as you would seem abnormal by not aging.
Either way, it would be a difficult life to live. So if you are one who seeks love and lifelong companionship, you'd likely not want it. If you're someone who's non committed and would prefer short relationships and one night stands, that would likely be a better choice for you.