The easiest way to avoid the 'doghouse' is really very simple. If you love someone unconditionally, and they love you back, your everyday actions will show her she is appreciated.
I'll use an example that I have take out of context but I think works well here.
There's a large, empty jar. If you fill it with golf balls, the jar will become full. However, you can add some marbles to fill in the gaps between the golf balls. This will also make the jar full. After the marbles, you can fill the remaining gaps with sand and, once again, the jar is full.
The golf balls represent the small, important things in a relationship; telling her you love her, comforting her when she's sad, being supportive in her decisions.
The marbles represent kind, small gestures; taking an interest in her interests, rubbing her back or feet, asking her how her day was.
The sand represents the grand gestures; taking her for a meal, buying her a nice gift, surprising her with a weekend away.
If you fill the jar with the sand first (or in your case, show her you care buy taking her for meals and buying things for her) there's no room for the golf balls or marbles. This means the little things you do, like telling her you love her or asking how her day was, she won't notice and become meaningless to her.
You need to make sure you pay extra attention to the important things that will make her feel appreciated. Telling her you love her every day goes a long way to showing her you care. Asking her how her day was shows you appreciate how she's feeling. And there's always room to take her for a meal once in a while just to show her she's worth the effort. If you do the little things every day, she will realise how much you appreciate her and in turn, will appreciate you for it. You can always set a reminder on your phone or make a note on your calander to make a nice gesture, just so you won't forget.
If she doesn't take note of the little things, and takes you for granted, remind her of the things you do for her, tell her that YOU feel unappreciated. A relationship is a two way street, there has to be give and take.
At the end of the day, if she loves you, she won't need grand gestures to feel appreciated. If she only feels appreciated when you buy her things or pay for meals, perhaps you need to take a minute to think if she's worth your time.
All the best.
The world and it's mother could give you all the advice they have, but the outcome will always be in your hands.