How should you fight
Personally I would back this query line up a bit and instead suggest asking, "How should you fight with someone?"
Because as everyone has noted here, love is work - hard work. You have to put forth effort. You have to show up, communicate, reciprocate, and stick with it. And at some point - not if, but when - you'll hit a snag and you're going to fight. It's inevitable, but also healthy and part of every relationship.
Most people know the obvious how not to fight (i.e. avoid physical or emotional abuse), but here are my recommendations for how to:
1) Don't expect anyone to read hints or emotions, say things out loud and as clearly as possible
2) Let your emotions go at some point and focus on the facts - what really set you off? Why? Identify this and point it out to your partner
3) Direct your complaints at the person involved, rather than venting your frustrations to everyone else under the pretense of asking advice. There's advice, and then there's avoidance. Confrontation's gotta happen sometime, and your partner deserves to be in the ring with you when it does - not blindsided by a hung jury of your peers.
4) Don't bottle up your frustrations, voice them as they occur. This way you're not blowing up out of the blue at someone and catching them completely off guard (or worse, on a bad day)
5) Don't take things personally - people are human and flawed. Theys often do things out of thoughtlessness, carelessness, preoccupation, or plain misunderstanding as often as they do out of spite. While this may not offer much comfort, it's much easier to correct someone for being dumb than for actively hating on you.
6) Identify how you and your partner handle stress / criticism and note this to each other (again, out loud) so you can both understand where the heck your ridiculous behaviorial quirks come from. Note: This does not excuse said quirks, it instead provides you the guidelines of what to watch out for and how to navigate potential minefields.
7) Always plan ahead - fights should never repeat, otherwise you can't make any progress. Each argument should end with an action plan identifying exactly what changes you are both going to make to avoid the same problem in the future.
8) Make up sex. Just sayin'. It helps re-forge the bond of your relationship, and it's also pretty hot. Skip this step if the relationship isn't romantic, the above points are still good.
If you're wondering if you can really love someone, then simply ask yourself if they're willing to go through any of the steps above to stick it out with you. If the answer is no, then maybe try a different sparring partner on. You might be amazed at the difference you'll see in the long run between having someone who just shuts down on you whenever you raise your voice, versus having someone who's willing to open up, yell back, roll their eyes, and then work it out and move forward. I definitely was, and everyone thinks I married a demon. Little did they know how refreshing a hot temper can truly be.