It is often because they see no future for themselves, at least not a happy one.
Since the future is bleak, they decide to end the suffering here and NOW.
So, having images about the future is only natural. And if they are happy images, even better.
Living for now doesn't make sense. You do that when you're afraid of responsibility.
The future is always a challenge.
When will you get married? How many kids will you have? What level of education can you afford? Where will you live? What kind of job and income will you end up with? Will you be happy with this woman in 10 years time?
All of that seem like tough decisions. So, a lot of people decide to live for now and not worry about those tough questions.
Unfortunately, you can't wish them away. If you don't think about them now, that future you fear will eventually catch up with you.
The right thing to do?
Think about the future. Plan for it.
I'm glad that you see a happy future with your dream woman. Happiness is the reason why we live.