Your best bet is to put all your time and effort into someone who seems like the worst possible match for you and makes you physically angry. Odds are that in the end you’ll find very little connection with this person, yet somehow find a deeper relationship than you would have with someone you actually liked.
A good way to solidify a relationship is by doing something very dangerous together, such as swinging over a chasm or terrorizing a young woman in a torture scenario.
If a guy seems like a total asshole, the most likely reason is because he was such a super nice guy that he allowed himself to be hurt in some way and is now protecting himself from getting hurt again. He is also very aware of this fact. But if you can break through this layer of protection, nearly every asshole is extremely nice. Except for the real assholes, who are the ones that appear to be very nice but then get super angry when you go on a date and accidentally spill a drink on them.
If you need romantic advice, consult your goofiest friend. There’s a good chance that she had an analogous relationship that she will explain, it will make you feel better, and then at the wedding montage near the end you’ll see her hooking up with a groomsmen and say, “Here we go again!”
Try doing something insane like climbing the tree outside your lover’s apartment. They will catch you, and normally this sort of thing would be inappropriate and frightening, but all will be forgotten quickly and then you can really get to the love part.