Who says the spark has to fade away over time?
Each person needs to address his/her own fears in the relationship. The pursuer needs to find a way to cope with his/her fear of abandonment and make emotional space for the avoider to take action. The avoider needs to face his/her fear of being overwhelmed emotionally and bridge the emotional gap between him/her and the pursuer. Finding a healthy balance is attainable.
2. Be respectful of yourself and your partner at all times. Take a time out if you feel angry or resentful. Journal about your resentments and try to find a solution before talking to your partner. Learn to articulate your feelings in a non-threatening way. Be ready for your partner to say your solution doesn't work. Ask for his/her solution; he/she might have a great idea. Be a safe person for your partner. Your partner can be your best ally and friend.
3. Choose to bring novelty to your relationship. Bring home flowers, take each other on a date, go on an adventure together, spend time doing a project together, ski, hike, bike, craft, take photos of birds — you get the idea.
It is vitally important to remember your goal of being satisfied in your relationship. Helping your partner feel emotionally safe with you is the key to your satisfaction in a long-term relationship. Bringing novelty will spark the flames of romance only if you both feel emotionally safe and connected.