have a long term relationship with someone and then marry them

I really want to do this. I think it’ll be a sign of maturity to be able to stick at relationship more than a couple of months. My track record isn’t exactly good. The longest i’ve been with someone is about a 8months.
Atm I’ve been with my current partner for just under three months. I really feel like this time I’m going to work at things. Like I’ve found the right person for me at the moment.
How long is a long term relationship? For me when I get to one or two years then I can really say that this goal has been completed.