Well, short answer is that you don't know, not really, not 100%. Okay yes, there are all of those initial fuzzy, glowy, feel good vibes that you get when you first hook up with someone, but you can also get those in short term relationships that turn to shit, so they really aren't the best indication that your relationship has the minerals to be everlasting and lifelong. I think that the only way that you can be somewhat certain in the beginning stages is when you have completely bared your mind, body and soul to a person and they still want in. And this type of baring of the self can take anywhere from 12 months to 20 years to establish (depending on your level of openness) so this is a pretty gradual process, an unfolding if you will. However, generally, anyone that can accept all of your flaws, love you unconditionally and accept you at your sickest, weakest and meanest moments is definitely worth considering as a life partner in my opinion.
Some couples stay together for years and years and still never really get to know each other very well, in fact this is more common than you might think. However, if both parties can be completely transparent with each other, I believe that this is really good start when it comes to laying a solid lifelong foundation of togetherness. However, just as equally important for longevity is common ground and similar values and ethics, because clearly a smack head and a deeply pious catholic, regardless of their ability to be transparent with each other are not necessarily going to make the best lifelong bedfellows are they? As a couple, you simply must have some ethical consistencies in order to thrive, without this there will never be smooth sailing and it is inevitable that the relationship will come to a conclusion, quite possibly an unpleasant one.
When all of the initial infatuation and fascination wears away (and it does because humans take things for granted - even really good relationships) if you don't have some common ground, united front and shared values, well honestly, you're gonna be fucked pretty quickly. And when I say common ground I mean something more substantial than both of you being into jasmine green tea. I'm talking ethics and general life philosophy. You don't need to be identical, but on some issues you will need to find common ground to be able to have harmony and longitude in your relationship.
And differences, well they're going to matter as well and regardless of how charming, attractive and wonderful your partner may be, you're going to need some space from them at times as well. Nothing wrong with sharing loads of quality time together, but the saying too much of a good thing can happen in relationships, so some seperation of time and interests is also important to keep things in balance. I for one would've left my husband years ago if we'd been working, resting and playing together all of the time, love him as dearly as I do, I don't want to be around him all of the time and our very different interests have ensured that we have both enjoyed some mutually appreciated 'away from each other' time.
But don't take my word for it, I've only been married for 25 years, what the hell do I know about long term relationships? Jokes, I do actually know a shit load about it and I definitely know that at the heart of it all, there are no guarantees with any of it. You can never be 100% sure that the person you choose to be with now will be the same one that you are going to want to wake next to in 10, 20 or 50 years time. And maybe that uncertainty, that gamble that you take with your own heart, that leap of faith into the unknown, maybe it is just another part of the magic and joy of it all anyway.
I do however know that staying in a meaningful long term relationship takes lots of work and a great deal of compromise and a shit tonnes of your own personal time; and there will be times when it feels like none of the effort is worth the struggle, but trust me when I say that it is. That for every rough day there will be a grand day and for every struggle that you endure together you will become stronger and more aware of each others truths and lives. And as long as one of you is always in there batting for you both to stay together, then odds are that you probably will. Odds are that you'll wake up and look at your perfectly imperfect partner one day and wonder how you could ever manage a day without them, and I suppose that will be the day that you can know for sure that they are the one that you want; hopefully forever.

Release Date: 2008
Rating: MA 15+
Running Time: 120 mins
Filmed and set in India, directed by Danny Boyle and written by Simon Beaufoy, Slumdog Millionaire was a sleeper hit, universally adored by audiences for its interesting plot, lively soundtrack and touching sentiments. Slumdog Millionaire went on to sweep the Academy Awards, winning Best Picture and Best Director, and also had great success at the BAFTAs, Golden Globes and Critic's Choice Awards, quickly becoming the must see movie of 2009.
Jamal Malik (Dev Patel) is a participant on an Indian version of Who Wants to be a Millionaire? Each question links Jamal back to an event in his life, which is vividly recalled for us before he answers each question. As Jamal gets closer and closer to becoming a millionaire, and suspicions arise that he is cheating due to his amazing ability to answer even the most obscure questions, it becomes apparent that his reasons for being on the program are mainly linked to the long lost love of his life.
This is an exhilarating movie with a wonderful plot line and a lot of heart. There is so much inspiration to be gleaned from Jamal's tale of hardship and endurance, it was hardly surprising that this movie won a place in so many hearts, it won a place in my own as well. You'll laugh, you'll cry and by the end of it you'll want to go to a Bollywood dance lesson, there is nothing like it, it's a must see for sure.
FINAL SAY: I'll wait for you at the train station every day at five.
4.5 Chilli Peppers