Love is really simple.  Oh we often think it's difficult, especially when someone is "being difficult."  It boils down to this:  recognizing that the other person is no better or worse than we are, whatever the circumstances of their life or ours, seeing them as they are and accepting them -- while loving our self.. 

Behaving lovingly is often harder..  Life places a lot of demands on us, and we are often tired and just plain old crabby.  Moreover, we learn, or do not learn, how to behave lovingly from our family, our schools, our churches, movies, books, friends.  Those aren't always right.  So some of us think w are behaving lovingly when we never confront someone else with anything.  Others think we are behaving lovingly by never enabling anyone ever.  Still others think loving behavior is never denying anyone anything.

The fact is that one can have the most loving feelings toward someone, but if one does not behave lovingly toward them, they will not feel loved.  So what is loving behavior?

1.  You must really SEE the person for who they are, not who you want them to be, and they must know that you see them for who they and ACCEPT them as they are. A mother who wants a daughter who is a "girly-girl" and dresses her in bows and ruffles, only to have her "tomboy" daughter go off to play and come home with the ruffles ripped because they caught on a limb when she climbed a tree should probably bite her tongue instead of scolding her daughter for ruining the dress.  That mother should also probably shift her thinking about her daughter's wardrobe.  Similarly, a father who wants his son to share his love of hunting and fishing when the son would rather stay home and read books would do well to never make the son's differing interests an issue of criticism.  Children are, after all, their own selves, not clones of their parents.
2.    Find a way to connect with the person on their terms.  Show an interest in what they are interested in.    Really listen; remember what they say.  Know what is important to them and show that it is important to you for them, even it isn't something important to you at all.  Example:  Astros baseball was really important to my mother.  I'm not a big organized sports fan, although Astros baseball comes closest.  I would make a point of commenting on games, the win/loss ratio, ask "what about that play by So-and-so in the ___ inning?  Wasn't that something?"  The point wasn't to make it look like I was interested, but to let Mother know that I knew she loved it.
3.  Be honest but tactful.  Use humor if possible.  When your wife asks "Does this dress make my ass look fat?"  Don't say no if it does.  Instead say something like "I think the blue one showcases your delectable derriere better, but any dress you wear will make your ass look fat, honey, cause I AM fat!"  If you aren't fat, opt for something like walking up next to her and deadpanning  "You tell me...does it make me look fat?"  Above all do not volunteer criticism if it isn't solicited! 
4.  Express anger, frustration, and other negative emotions brought about a conflict in terms of your self.  Say "I feel really angry when you ....  I think it's because of ___________.  I would appreciate it if you tried not to do that until I have worked through this issue."  Some issues you may never work through, but this speaking pattern tends to defuse volatile situations rather than accelerate them.
5.  Celebrate the events that are positively important to them.  Sympathize with the events that are negatively important to them.  When I published my first article, my mother said "Oh that's nice."  How I longed for "That's wonderful!  I'm so proud of you."  When my first love died when I was 19, Mother said "Well, it's not like you were married to him.  Go take care of your brother  (who was going through a divorce.)"  Now, I know my mother loved me, but I also know she had no clue how to talk to me to make me feel loved.