When someone is searching for a soul mate/partner/spouse etc. they mostly look for people who have similar qualities to them. This way, they are more compatible, thus have more things to talk about, share similar interest, and tend to be passionate about similar things.

In this sense, I don't think that a couple must entirely be vegan or vegetarian to be in love. I do think that it helps. But the diet that you chose should not make so much conflict at the dinner table mainly discussing the indecision about whether meat should be kept in the house. However, you don't pick your significant other due to diet; you (hopefully) pick them based on characteristics that you admire. Hopefully you enjoy their charisma, personality, looks, etc. Their moral stanza is something different, you may not agree on ethics but it’s not your sole choice. Many people from different races, ethnicities, religion, etc. come together in relationships. They grow by challenging each other. As a couple, people develop views based on learning information. They do not solely accept their own view and declare it right. Couples are meant to challenge each other.

So do I think diet choice affects the relationship? No, I would not mind living with a meat eater. However, my mind is set on my own ways and I won't give up veganism for the sake of a relationship, nor do I expect my partner to change their ways for my benefit. Iwould encourage them to live a holistically healthy lifestyle which would limit the amount of meat that they eat, but I wouldn't enforce any ideas. 

What has helped my with this "open-minded" philosophy is that I live with my family, none of them are vegan or vegetarian for that matter. This has helped me grow as a persona and show respect and restraint for other people. If you value other individuals, you will learn to respect and value their beliefs. Not everyone is the same. For example, siblings raised by the same parents develop their own personalities and experience different things in life that shape them into the individuals that they become.

Veganism is essentially a lifestyle, not a diet. So to make someone change their lifestyle is difficult. You can incorporate things that will benefit your significant other; however,you are not going to change their daily habits.
Todays eats:
bf: 5-6 c papaya
two medjouls

snack: grapefruit

lunch: pear, baby carrots, mamey and banana smoothie
1 medjoul

dinner: fava bean soup (500ml), tomato

dessert: apple with pb and 4 dates